Geology, Earth science, Minerals, Rocks, Ores, Clay.

School Science Lessons
2024-06-22

Geology Earth sciences
(UNPh35) Contents
35.1.0 Rocks
35.2.0 Minerals

35.1.0 Rocks
35.1.2a Rocks, Igneous, Metamorphic, Sedimentary
35.1.3 Cleavage, fracture, twin crystals, crystal face
35.1.4 Colour of rocks and minerals
35.1.5 Crystal systems, crystal habit, crystal form
35.1.6 Feel and conductivity
35.1.7 Grain size and roundness
35.1.8 Hydrochloric acid test, effervescence test
35.1.9 Lustre (metallic lustre, non-metallic lustre)
35.1.10 Magnetism test
35.1.11 Odour and taste
35.1.12 Shape or form
35.1.13 Streak
35.1.14 Tenacity
35.1.15 Touchstone, gold streak
35.1.16 Transparency (transparent, translucent, opaque, refraction)

Minerals
A mineral is a naturally occurring inorganic substance obtained by mining, having distinctive chemical and physical properties.
Mineral wool, rock wool, stone wool, mineral fibres, is used for seed germination, insulation, filters.
Adamant, is a traditional term for a very hard rock, especially diamond or corundum.
Mafic minerals are rich in Mg or Fe, rocks rich in ferromagnesium minerals.
Mineral salts, food additives
Actinolite
Agate
Albite, NaAlSi3O8
Alkaline feldspars
Amber
Amethyst
Amosite
Amphibole
Anatase
Andesine
Anglesite
Anorthite
Antimony
Apatite
Aragonite
Arsenic
Asbestos
Aquadag
Augite
Azurite
Baryta
Barytes
Bauxite
Bentonite
Beryl
Biotite mica
Birth stones
Bismuth
Borax
Bornite
Bustamite
Cadmium
Calcite
Calomel
Celsian
Coal
Carbonates
Carving stones
Cassiterite
Cerussite
Chalcanthite
Chalcedony
Chalcocite
Chalcopyrite
35.3.1 Charcoal blocks
Chromite
Chrysoprase
Chrysotile
Cinnabar
Coal
Coltan
Copper
Coprolites
Coronadite
Corundum
Covellite
Crocidolite
Crocoite
Cryolite
Cuprite
Diamond
Dolomite
Emerald
Emery
Epsomite
Erinite
Feldspars
Fluorspars
Fluorite
Fuller's earth
Galena
Garnet
Goethite
Gold
Glauberite
Graphite
Greigite
Gypsum
Halite
Halloysite
Hausmannite
Haematite
Hornblende
Hyalite
Hydroxyapatite
Illite
35.6.9 Isostasy models
Iron
Ilmenite
Jadeite
Jasper
Jet black
Kalinite
Kaolinite
Kerargyrite
Kyanite
Langbeinite
Lapis lazuli
Lead
Lead paint
Lead tetra-ethyl
35.3.5 "Lead pencils"
Limestone
35.6.14 Tests for limestone
Limonite
Magnesia
Magnetite
Malachite
Marble
Marbelite
Marcasite
Mascagnite
Meerschaum
Melanterite
Mercury
Mica group
Microcline
Millerite
Minium
Mirabilite
Molybdenite
Monazite
Montmorillonite
Moonstone
Muscovite mica
Nacre
Nahcolite
Natron
Nephrite
Nickel
Nickeline
Obsidian
Olivine group
Onyx
Opals
Orpiment
Orthoclase feldspar
Pegmatite
Periclase
Perlite
Perovskite
Perthite
Petroleum, crude oil
Palagonite
Platinum
35.5.9 Pozzolana. (puteolanum)
Pyrite
Pyrolusite
Pyromorphite group
Pyrrhotite
Quartz
Quartzite
35.6.12 Quicksand
Realgar
Rhodochrosite
Rhodonite
Rock crystal
Rose quartz
Ruby
Rutile
Sanidine
Sapphire
Scheelite
Selenite
Serpentine
Siderite
Siltstone
Silica
Silicates
Silicates
Silicic acid
Silicon
Silicon compounds
Silver
Slate
Smithsonite
Sodalite
Sphalerite
Spinel
Spodumene
Stibnite
Stilbite
Stone dust
Strontium minerals
Struvite
Sulfur
Sunstone
Sylvite
Talc
Tanzanite
Tellurium
Thorite
Tin
Tin
Titanite
Titanium
Tobermorite
Topaz
Trona
Tschermignite
Turquoise
Ulexite
Uraninite
Uranium
Valentinite
Vermiculite
Witherite
Wolframite
Wollastonite
Zeolite
Zeolite
Zinc
Zinc blende
Zincite
Zircon
Zirconium

35.1.1 Rocks
Rocks are any naturally occurring aggregate of one or more minerals and are classified by origin as follows:
1. Igneous rock formed by volcanic activity,
2. Sedimentary rock formed from sediments and,
3. Metamorphic rock formed mainly by heat and pressure on original rock.
Minerals were originally the substances obtained by mining, but, to a geologist, a mineral is a naturally occurring inorganic solid with a certain chemical composition and physical properties, including an ordered internal structure.
A mineral has a definite chemical composition and may have a characteristic shape.
A rock is a composite of more than one mineral.
Pieces of the same rock might be composed of different minerals.
Some rocks are composed of elements, e.g. gold or silver, but most rocks are combinations of elements in minerals.
For example, the mineral quartz is a combination of the elements silicon and oxygen, SiO2.

Use the following testing and descriptive techniques to identify minerals.
Mineral classification:
| 1. Elements | 2. Sulfides (selenides, tellurides, arsenides, antimonides, bimuthides) | 3. Halides | 4. Oxides, hydroxides | 5. Nitrates, carbonates, borates | 6. Sulfates (chromates, molybdates, wolframates) | 7. Phosphates, arsenates, vanadates | 8. Silicates | 9. Organic substances.
Mineral origin:
| 1. Crystallization from magma, e.g. magnetite, mica, quartz | 2. Physical, chemical and biological changes caused by weathering, e.g. serpentine, malachite | 3. Sedimentary and evaporation processes, e.g. rock salt, calcite | 4. Biological accumulation of salts, e.g. limestone, pyrite |.

35.1.4 Colour of rocks and minerals
The colour is an obvious physical property, but it varies too much to be a reliable property for identification.
Rock colour charts are available, usually based on the "Munsell colour chart".
The names of some colours come from the characteristic colour of minerals, e.g. emerald, ruby, azure, amethyst.
Emerald, Be3Al2(SiO3)6, natural emerald
Quartz, calcite and rock salt are colourless if they do not contain impurities.
However, some pure minerals may have different colours, e.g. fluorspar, apatite and beryl.
Colour of minerals may be changed by sunlight, artificial light, ultraviolet light, turning in the light, radioactivity, surface tarnish, heat, and dyes.

35.1.9 Lustre (metallic lustre, non-metallic lustre)
The lustre is the appearance of the surface of a mineral in reflected light, depending on the reflection and refraction of light.
The lustre often distinguishes minerals from one another.
Minerals are divided into two great groups on the basis of their lustre.
One group is opaque and has a metallic lustre like that of a metal.
The other group may be opaque or transparent, but does not have a metallic lustre.
Most of the ore minerals have a metallic or a sub-metallic lustre, but others may be vitreous or glassy; resinous (like resin), pearly or silky.

Minerals may be:
1. opaque and with a metallic lustre, like a metal, e.g. pyrite, galena,
2. opaque or transparent, but without a metallic lustre.
Subdivided as: | adamantine (diamond-like) lustre | vitreous (glassy) lustre | greasy (oily) lustre | dull lustre | silky lustre, e.g. asbestos | pearly lustre (layered) |.
A gem with changeable lustre, chatoyancy, is called a cat's eye, e.g. chrysoberyl, a form of quartz.
The lustre of a diamond used in jewellery is called its "water", so jewellers call the best diamonds "the diamonds of the first water".

35.1.16 Transparency (transparent, translucent, opaque, refraction)
Transparent minerals allow passage of light without much deviation or absorption, like window glass.
You can read through a transparent mineral, e.g. quartz (rock crystal), rock salt, topaz.
Each transparent mineral has a characteristic refractive index.
Translucent minerals allow passage of some light, but not images, e.g. frosted glass used in bathrooms.
Translucent minerals may be a transparent mineral containing impurities or finely granular transparent minerals.
The minerals gypsum and mica may be translucent or opaque if finely granular, but transparent if big crystals.
Opaque minerals allow no passage of light in thin section and have a metallic or dull lustre, e.g. pyrite.
An anisotrtopic crystal may split incident light to produce double refraction, e.g. calcite crystal.

35.1.5 Crystal systems, crystal habit, crystal form
See diagram 35.8.1: Orthogonal axes.
See diagram 35.8.2: Non-orthogonal axes.
See diagram 35.8.3: Crystal habit.
See diagram 35.8 4: Crystal form of the seven crystal systems.
Most minerals are crystalline, but some minerals are amorphous, non-crystalline.
The patterns of the internal atomic structures result in a definite external shape.
However, silica, SiO2, may occur as quartz crystals, irregular sand grain crystals, fine grain chalcedony aggregate, and amorphous opal deposit.

Crystal habit refers to the relative width and length of the crystal faces, i.e. the development of the faces of a crystal.
Crystal habits: | pyramidal habit, e.g. native sulfur | columnar habit, e.g. calcite, tourmaline, gypsum | tabular habit (flat slab), e.g. mica | acicular habit (needle-like), e.g. malachite, gypsum, rutile | fibrous habit, e.g. asbestiform fibrous hydrated silicate minerals are hazardous in the air | lamellar habit (plate-like), e.g. muscovite, biotite, chlorite | prismatic habit (elongated), e.g. most silicates, hornblende |.
A similar term, "crystal form", refers to the geometric shape of the crystal.

When looking at a crystal:
| "axis a" is "front to back" | "axis b" is "right to left", and | "axis c" is "top to bottom"|.
Orthogonal axes are mutually at right angles, i.e. the cubic, tetragonal, and orthorhombic (rhombic) crystal systems.
Non-orthogonal axes have one or more axes not at right angles to the others, i.e. the monoclinic and triclinic crystal systems.
The hexagonal and trigonal crystal systems have three horizontal axes mutually at 120^o and at right angles to the vertical, axis c.
Let α = angle between axis b and axis c, β = angle between axis a and axis c, and γ = angle between axis a and axis b.

The seven crystal systems and examples of crystal form (geometric shape of the crystal):
1. Cubic (isometric): a = b = c, and α = β = γ = 90^o, e.g. galena, garnet, halite, fluorite, magnetite, pyrite, sphalerite, uraninite
2. Tetragonal: a = b not = c, and α = β = γ = 90^o, e.g. cassiterite, chalcopyrite, rutile, scheelite, zircon
3. Orthorhombic: a not = b not = c, and α = β = γ = 90^o, e.g. barytes, marcasite, olivine, stibnite, sulfur
4. Monoclinic: a not = b not = c, and α = γ = 90^o not = beta, e.g. augite, gypsum, hornblende, micas, orthoclase feldspar, serpentine, talc
5. Triclinic: a = b = c, and α not = β not = γ e.g. axinite, plagioclase feldspar, rhodonite
6. Hexagonal: a = b not = c, and α = β = γ = 90^o, e.g. apatite, beryl
7. Trigonal: a = b not = c, and α = β = γ not = 90^o, e.g. ilmenite, tourmaline.

35.1.3 Cleavage, fracture, twin crystals, crystal faces
See diagram 35.9: Cleavage.
1. Cleavage is the tendency to split along certain definite planes, and is a very useful distinguishing property that reflects the crystalline structure of a mineral and which can be related to the packing together of its atomic constituents.
Minerals may cleave in one, two, three or more directions with various degrees of perfection.
A cleavage occurs when you can split a mineral in a plane parallel to a crystal face leaving a smooth flat surface along this planes.
Some minerals have only one cleavage direction, e.g. mica, but other minerals may have two or more cleavages, e.g. galena has three cleavages.
The direction of cleavage may be indicated by fine cleavage rifts running along the planes of cleavage.
Some fine grain rocks have a cleavage, e.g. slate.
2. Fracture is any breakage or rupture other than a cleavage.
Some minerals break evenly, others have an uneven or jagged hackly fracture.
The fracture may feel even, uneven, jagged and conchoidal.
Conchoidal is the shell-like pattern seen on chipped glass.
The fractures are curved as often in quartz.
3. Twin crystals may occur in a regular way with internal angles consistently at more than 180^o, e.g. fluorite, gypsum, cassiterite.
4. Crystal faces may have characteristic striations, e.g. pyrite, quartz, and tourmaline.

35.11 Relative density, RD (formerly specific gravity)
The relative density, RD, of a mineral is a number that expresses the ratio between its mass and the mass of an equal volume of water at 4^oC.
If a mineral has a relative density of 2, it means that a given specimen of that mineral has twice as much mass as the same volume of water.
Most common minerals have a relative density of 2.5 to 4.0.
The following substances have their densities expressed in g / cm³: | sulfur 2.0 | quartz 2.6 | calcite 2.7 | copper 8.9 | lead: 11.35 |.
Some ores are not uniform in density, because they contain variable quantities of quartz, feldspar and other minerals, e.g. malachite, cassiterite and cerussite.
Minerals less than 2.5, feel "light" and those more than 3.0, feel "heavy" for their relative size.
The relative density of a mineral of fixed composition is constant and its determination is frequently an important aid in identification of the mineral.
To find the relative density of a mineral, it must be pure and compact, with no cracks or cavities where bubbles or films of air can exist.

35.1.13 Streak
The streak refers to the colour of the ground or powdered mineral and is sometimes a reliable test.
To see the streak, rub the mineral on a ceramic streak plate or building tile or unglazed porcelain to leave a coloured scratch.
Porcelain has Mohs scale hardness 6-6.5, so harder minerals will only leave a streak of white porcelain powder.
Grind the harder minerals to see the streak colour.
The colour of the streak may be different from the colour of the gross mineral in the ground.
Colourless and white minerals always have white streak.
Minerals with metallic lustre show the difference between true colour of the mineral and streak colour, e.g. black haematite gives a red streak powder.
A mineral usually has a constant streak colour, even if the colour of the mineral varies.
So streak is much more reliable quality than colour of the mineral.
The iron mineral haematite gives a brick red streak and limonite gives a yellow streak.

35.1.15 Touchstone, gold streak
Touchstone is a schist, used to assay gold by comparing the streak of the sample to the streak of "touch needles" with known gold content.

35.1.8 Hydrochloric acid test, effervescence test
Cold, dilute hydrochloric acid causes bubbles, effervescence, with sedimentary rocks containing carbonates, i.e. limestone, e.g. calcite CaCO3, dolomite Ca(CO3).Mg(CO3), witherite BaCO3, malachite CuCO3Cu(OH)2.

35.1.10 Magnetism test
Note whether the powdered mineral is strongly or weakly attracted to a magnet, e.g. magnetite Fe3O4, attracts iron dust.
Haematite becomes magnetic when heated.
Palaeomagnetism is the study of the magnetic record in ancient rocks, e.g. changes and reversals in ancient magnetic fields of the Earth.

35.1.11 Odour and taste
Some minerals have a characteristic odour when rubbed, e.g. arsenopyrite FeAsS, fluorite.
Sulfur has a distinctive odour, clay minerals have an "earthy" smell.
Minerals soluble in water have a characteristic taste.
Some people claim that the amalgam fillings in their teeth allow them to taste certain minerals.
A "metallic taste" in the mouth may be caused by antibiotics, drugs, oral diseases and even mercury poisoning.
Usually the metallic taste disappears within days.
Some common examples of odour and taste include the following: Chalcanthite, sweet metallic taste and slightly poisonous, CuSO4.5H2O, it is a water-soluble sulfate,
Epsomite, Epsom salts, bitter taste, MgSO4.7H2O, hydrated magnesium sulfate,
Glauberite, bitter and salty taste, Na2Ca(SO4)2, sodium calcium sulfate,
Halite, rock salt, saline taste, NaCl,
Hanksite, salty taste, Na22K(SO4)9(CO3)2, sodium potassium sulfate carbonate.
Melanterite, sweet, astringent and metallic taste, FeSO4.7H2O, hydrated iron sulfate.
Sylvite (sylvine) bitter taste, KCl.

35.1.6 Feel and conductivity
Experienced handlers of minerals, e.g. gemstone workers, claim to be able to recognize minerals from the feel against the fingers or the cheek.
For example talc and graphite may feel smooth and greasy, while, (China clay), and chalk feel rough and dry.
Copper feels colder than amber against the cheek, because copper is a better conductor of heat.
Similarly, real gemstones can be distinguished from glass imitations by feel against the cheek.

35.1.12 Shape or form
Minerals may be found in a number of different shapes.
They may be crystals, parts of crystals or groups of crystals, which may be just massive or grouped haphazardly or in a particular way.
If the crystals radiate from a point we may call them radiating.
They may form networks or be reticulated.
Tree-like or moss-like shapes are described as mossy or dentritic.

35.3.1.0 Minerals mined at the Broken Hill mines, Australia
The minerals of Broken Hill are world famous, because many of them are rare and beautiful.
Most rare minerals were found in the top sections of the mine, where sulfide ore minerals had been weathered and oxidized by groundwater to produce a dazzling array of secondary minerals.
However, these areas of the mine are long worked out and are not producing ore or mineral specimens.
1. Ore minerals of the primary (sulfide) zone
2. Gangue (waste) minerals of the primary (sulfide) zone
3. Ore minerals of the oxidized zone

Ammonium
Struvite, [(NH4)MgPO4.6H2O], ammonium magnesium phosphate
Tschermignite, NH4Al(SO4)2.12H2O, ammonium alum

35.2.3 Ammolite (aapoak, Kainah, gem ammonite, calcentine, korite), one of the rarest gemstones, is found in Alberta and on slopes of Rocky Mountains, is composed of fossilized shells of ammonites, mostly aragonite crystals as in nacreous pearl shell, specific gravity 2.6-2.9.
Pearly flashes of red, green and blue iridescence from polished ammolite is caused by interference of light rebounding through layers of aragonite.

35.2.14 Borax mineral, [Na2B4O5(OH)4].8H2O, Tincal, found at edge of borax lakes.
Borax has a sweet alkaline taste, hydrated sodium borate, di-sodium tetraborate (III)-10-water, Na2B4O7.10H2O or Na2(B4O5)(OH)4.8H2O, occurs in evaporite deposits, salt lakes, playas and efflorescence on soils in arid regions, in solution in some hot springs.
Ulexite, alkaline taste, NaCaB5O6(OH)6.5H2O, hydrated sodium calcium borate hydroxide, is found associated with borax, often in evaporated lakes.
When ulexite is polished and has two smooth sides, it has the fibre optic property of projecting an image through internal reflection from the bottom of the to the top, so some people call it "TV stone"!
The ulexite fibres have the formula B5O6(OH)6.

35.2.7 Feldspars group, "field stone", - (AlSi3O8)
Feldspars occur as aluminosilicates of alkali metals and alkaline earths, have pink colour, but red-green or yellow colour if impure and some are white.
For example, albite, NaAlSi3O8, Mohs scale of hardness 6, white streak, glassy lustre, good cleavage in two directions, conchoidal fracture, SG 2.55-2.76.
Aluminosilicates are the most common rock forming silicate in igneous rocks and some sedimentary rocks.
Feldspars are used in the interior of buildings as an ornamental veneer.
Feldspars have dull surfaces, unless light strikes at just the right angle.
Feldspars in rocks may cause flashes of light, because of reflection from two directions of cleavage at right angles to each other.
Feldspars are used in glazes and the manufacture of glass, enamels, polishes, and roofing material.

Feldspars are divided into two groups:
Group 1. Alkaline feldspars
Alkaline feldspars (K, Na)AlSi3O8, include orthoclase feldspar, microcline (KAlSi3O8), and sanidine, contain more potassium and less or no sodium, calcium may substitute for potassium and sodium, monoclinic or triclinic crystal system, crystals prismatic to tabular (also as irregular grains or cleavable masses), vitreous to silky lustre, colourless, white or pink (also green), white streak, Mohs scale of hardness 6, two perfect cleavages at close to 90^o, cleaves rather than fractures, not ferromagnetic, does not react with hydrochloric acid.
Sanidine and orthoclase feldspar are the high temperature alkali feldspars, occur in alkali-rich igneous rocks, e.g. rhyolites and granites.
Microcline, the lower temperature alkali feldspar variety, occurs in granites, pegmatite dikes and hydrothermal vein deposits.
Orthoclase feldspar and microcline also occur in some metamorphic rocks and as discrete grains in immature sandstone.
Minor colourless or white plagioclase intergrown with pink microcline is called perthite.
Group 2. Group 2. Plagioclase feldspars
feldspars, NaAlSi3O8, include albite, anorthite, and andesine contain less or no potassium, triclinic crystal system, tabular crystals (also as irregular grains or cleavable masses), vitreous to silky lustre, white to grey colour (also blue to green), white streak, Mohs scale of hardness 6, two perfect cleavages at close to 90^o, cleaves rather than fractures, not ferromagnetic, does not react with hydrochloric acid, occurs mainly in mafic and intermediate igneous rocks, e.g. basalt, andesite.
Experiment.
Note the pink colour and cleavage, then turn the specimen in the light and note flashing surfaces.
To distinguish the two groups, the alkali feldspars all have the perthite structure and plagioclase feldspars have lamellar twinning.
Note the fine lines on a cleavage surface of plagioclase feldspar, but not on orthoclase feldspar.
Feldspars include the following:
* Potassium feldspar, K-feldspar, orthoclase feldspar, orthoclase, KAlSi3O8
(Greek orthoclase straight fracture, because cleave planes at right angles)
Brown to colourless, vitreous pearly lustre, translucent to transparent, Mohs scale of hardness 6-6.5, specific gravity 2.55, good cleavage, brittle, uneven fracture, massive granular crystals, monoclinic system, main constituent of many different rocks, especialy igneous rock, e.g. Moonstone
* Moonstones, K(SiAl)4O8, feldspar, gemstone have blue-white spots with a silvery colour like moonlight.
Moonstone is silvery-white, or milky white with a soft blue shimmer moving across its face as the stone is moved, called "adularescence".
The distinctive shimmer, caused by tiny albite inclusions, reflect and scatter light, mimicking the moon's glow, hence the gem's name.
* Sodium feldspar, albite, NaAlSi3O8
* Calcium feldspar, anorthite, CaAl2Si2O8
* Barium feldspar, celsian, BaAl2Si2O8
* Sunstones, Ca(Al2Si3O3)Na(AlSi3O8), feldspar, gemstone.

35.2.12 Mica group
See: Mica (Physics and chemistry)
(biotite mica, Jean-Baptiste Biot, 1774-1863)
See diagram 27.6.4.8: Colours in mica (University of Melbourne).
This group has dark brown colour or is colourless (muscovite mica), Mohs scale of hardness 2.5-3, white streak, pearly to glassy lustre, single perfect cleavage, specific gravity 2.7, forms soft shiny flat flakes.
Muscovite mica or white mica, K2Al4Si6Al2O20(OH,F)4, contains no iron, so is clear and colourless.
Biotite mica, K2(Mg,Fe)6-4(Fe,Al,Ti)0-2(Si6-5Al2-3O20)(OH,F)4, is brown to black, and seen in granite as dark glittering specks.
Mica can be split into very thin elastic sheets that can then be split into thin transparent layers.
On split faces the lustre is bright and pearly white, but other faces are dull and rough.
Formerly, it was used in place of glass in beehives and in foundries, but now is used as a heat resistant material in windows, stoves, eye shields, and sparkling makeup.
Mica is a poor conductor of electricity so it is used in electrical appliances.
Mica is used as a filler in plasterboard and paint, as a surface coating on welding rods, a release agent for coating foundry moulds, and as spray-on decorative glitter.
Experiment
Crush the specimen and note the sparkling surfaces.

35.2.5 Hornblende, NaCa2(Mg, Fe²⁺, Fe³⁺, Al5(Si, Al)8O22(OH, F)2, in the amphibole group, has dark green to black colour, Mohs scale of hardness 5 to 6, brown to grey streak, glassy to dull lustre, two imperfect cleavages, uneven fracture, specific gravity 2.9-3.4.
It forms small dark green to black crystals and is seen with biotite mica as dark patches in granite.
Note the hexagonal cross-section of crystals, cleavage and colour of the hornblende specimen.

35.2.5a Actinolite, Ca2(Mg, Fe²⁺)5(Si8, O22)(OH, F)2, is a similar mineral to Hornblende.
Nephrite jade, Ca2(Mg, Fe)5(Si8,O22)(OH,F)2, is a fine grained massive variety of actinolite that is used for ornaments and sculptures and is the jade popular in China.
Jadeite, Na(Al, Fe)SiO6, NaAl(Si2, O6), pyroxene group, from Myanmar (Burma).

35.2.52 Olivine group (Mg, Fe)2SiO4, peridote, chrysolite
The olivine group has emerald-green to green-yellow colour, Mohs scale of hardness 6.5-7, white streak, glassy lustre, poor cleavage, conchoidal fracture, and specific gravity 3.2-3.4.
It weathers easily to leave the rock brown, because of iron oxide stain.
It occurs as sugary crystals that sparkle like quartz in basalt rocks.
Quartz and olivine seldom occur together in igneous rock.
Olivine occurs in the darkest rocks deficient in silicon.
It forms gemstone crystals, e.g. chrysolite, that are transparent and have a glassy lustre.
Volcanic "bombs" may have a lining of olivine crystals in the inner chamber.
Note the colour, hardness and density of the specimen.

35.2.16 Calcite, CaCO3, calc-spar, Iceland spar
Calcite has white colour, in cracks in sedimentary limestone, Mohs scale of hardness 3, white streak, glassy lustre, good cleavage in three directions (not at right angles), causing rhombohedral shape, conchoidal fracture, specific gravity 2.7 and greasy to touch.
Calcite occurs in four-sided crystals and as chalk and limestone.
It forms from evaporation of sea water, and occurs in sedimentary and metamorphic rocks, but not in igneous rocks.
The crystallized varieties always break into little four-sided pieces when hit with a hammer.
Iceland Spar is a clear crystal with refractive index 1.49 and 1.66, causing a double refraction effect, birefringence, double image caused by light polarization, used in the Nicol prism and in bomb-sights.
Sea animals use calcite to build a shell or outer skeleton.
Some types of calcite are used for building blocks, and for making lime and in the glass and steel industries.
Weathering of pyrite liberates sulfuric acid, and may change calcite into gypsum and other sulfates.
In limestone caves, calcite occurs as stalactites hanging from the roofs of limestone caves and stalagmites that grow up from the floor.
Ca(HCO3)2 (aq) --> CaCO3 (s) + H2O (l) + CO2 (g)
Note effervescence with cold dilute hydrochloric acid, hardness and cleavage.
Turn the specimen in the light and note flashing surfaces.
If the specimen is a clear crystal, place it on a line and observe the refracted double line.
Calcium minerals
Hydroxyapatite, Ca3(PO4)3OH, Ca10(PO4)6(OH)2, similar to bones, so bioactive and used in surgical implants
Perovskite, CaTiO3
Titanite, CaTi(SiO4)O, formerly called sphene, source of titanium dioxide, TiO2, used for white pigments in tennis shoes
Tobermorite, calcium silicatehydrate, Ca5Si6O16(OH)2.4H2O, in volcanic ash used in concrete for ancient Roman sea walls
Wollastonite, CaSiO3, calcium silicate, building material, used to make rock wool

35.2.29 Dolomite
Dolomite, Ca(CO3)Mg(CO3), [Mg, Ca (CO3)2], (+ some silica), calcium magnesium carbonate
Dolomite has colour white to pink, Mohs scale of hardness 3.5-4.0, glassy to pearly to dull lustre, white streak, good cleavage in three directions, SG = 2.84.
The term "dolomite" is a general term for rocks with a high ratio of magnesium to calcium carbonate.
Dolomite is used as sources of magnesium and in lining furnaces, fertilizers, ceramics, mineral wool, welding fluxes.
The medical use is to supplement calcium and magnesium deficiency.
Experiment
Note the colour, hardness, density, lustre, and slow reaction to dilute hydrochloric acid.

35.2.18 Carbonates, CO3^2-, mineral carbonates
Azurite, 2CuCO3.Cu(OH)2:35.2.10
Calcite, CaCO3:35.2.16
Dolomite, CaMg(CO3)2:35.2.29
Magnesite, MgCO3
Siderite FeCO3, chalybite, spathose iron
Smithsonite, ZnCO3:35.2.63
Witherite, barium carbonate, BaCO3
Malachite CuCO3Cu(OH)2:35.2.44
Calcite, dolomite and siderite are the main components of limestone.

Halloysite
Halloysite, Al4Si4(OH)8O10.4H2O, clay mineral, Dragonite, in plastics, flame retardants, paints
Chrysoberyl, Al2BeO4, alexandrite

35.2.6 Anglesite, lead sulfate, PbSO4
Anglesite has non-metallic lustre, but is adamantine when crystalline and dull earthy, Mohs scale of hardness 3, specific gravity 6.3 and is white, grey, pale yellow, transparent green, transparent to translucent colourless.
It may occur as groups of striated, blocky rhombs and flattened, simple, to complex prisms.
Anglesite is another widespread secondary mineral from the oxidized zones of the Broken Hill mine.
It is found in vughs (irregular voids) and fractures in all mines in the outcrop area.
The associated minerals are marshite, iodargyrite, pyromorphite, stalactitic goethite, and goethite matrix replaced by cerussite.

35.2.9 Arsenic, minerals containing arsenic
Arsenic, natural arsenic, As
Arsenic trisulfide, As2S3, orpiment, yellow pigment
Arsenopyrite, mispickel, arsenical pyrites, FeAsS
Anorthite, calcium feldspar, CaAl2Si2O8
Arsenolite, As2O3
Arsenopyrite, FeAsS
Erinite, Cu5(OH)4(As, O4)2, emerald-green, basic copper arsenate crystal, name from "Ireland"
Nickeline, niccolite, arsenical nickel, NiA:35.2.51
Orpiment, tinsel, deep yellow colour ("gold-pimented"), As2S3
Realgar, As4S4, arsenic sulfide, ruby sulfur, ruby of arsenic, non-metallic lustre, poisonous, red paint pigment, pesticide, "orpiment", highly toxic orange pigment

35.2.4 Asbestos
1. Asbestos is a group of fibrous silicate minerals, compact and hard, resembled petrified root of a tree, so called "mountain flax" or "salamander's wool".
asbestos (Greek amiantos incombustible)
Colours range from brown to yellow to green.
It usually occurs mixed with serpentine rock or mica schist.
Tiger's Eye and Hawk's Eye, used for men's cufflinks, are altered varieties of asbestos with wavy bands of light that glow and ripple as you move them.
Asbestos is a fireproof substance and formerly was widely used as a heat insulator, for packing and for fireproof garments and fabrics.
The main asbestos mineral is white asbestos or chrysotile, hydrous magnesium silicate, Mg3Si2O5(OH)4, in the serpentine mineral group.
Blue asbestos, crocidolite, is the most lethal to humans.
2. Inhalation of the short asbestos fibres can cause the lung disorder asbestosis, mesothelioma lung cancer and bronchiogenic cancer.
The manufacture and use of white chrysotile asbestos products, is banned in Australia in 2003, and since then is banned in many countries.
Fibro is an abbreviation for “fibrous cement sheet”, a fibrous material, commonly containing asbestos to reinforce thin cement sheets.
The most common types of fibro are flat sheets used for ceilings and walls, and corrugated sheets used for ceilings.
In Australia, the use of asbestos in fibro was phased out during the 1980s, and stopped entirely by 1987.
"Fibro" is a type of “bonded” asbestos, so there is no danger of asbestos fibres being released into the atmosphere.
However, general weathering, hail damage, fire damage, drilled fibro can make the asbestos “friable”, i.e. it can be breathed in.
Asbestos fibres may cause severe respiratory illnesses, mesothelioma, and lung cancer.
In Australia, asbestos can be tested and removed only by a licensed asbestos removal contractor.
Do not cut old "fibro" sheets or pieces of asbestos, but replace the whole sheets with non-asbestos sheets.
3. Asbestos is extremely toxic if inhaled into the lungs and causes two cancers, bronchiogenic carcinoma and mesothelioma.
It is safe to touch, but do not inhale the fibres.
Other forms of asbestos (amosite, anthophyllite, tremolite, actinolite and chrysotile) are not as dangerous by inhalation as crocidolite, but should be treated similarly.
Specimens of ash should be stored in a sealed container until collection by a licensed waste contractor.
Correctly embedded asbestos, as in geology teaching sample sets, does not pose a threat to health, provided that the embedding material remains intact.
4. In Queensland, Australia, asbestos samples sealed in plastic bags were in school minerals sets, but students opened the plastic bags and handled the asbestos.
The Queensland Government was forced to take out the asbestos samples from the school mineral sets.
Crocidolite asbestos is Not permitted in schools, so store demonstration specimens in sealed containers or embedded in plastic.
5. Classification of asbestos
Chrysotile, Mg3Si2O5(OH)4, white asbestos, most common use, in roofs, ceilings, walls, floors of homes, automobile brake linings, pipe insulation.
Amosite, (Mg,Fe)7(OH,Si4O11), brown asbestos, used in cement sheets, pipe insulation, insulating board, ceiling tiles.
Crocidolite, Na2Fe3Fe2[(OH, F)Si4O11]2, blue asbestos, tiger's eye, cat's eye, most lethal to humans, used to insulate steam engines, spray-on coatings.
Anthophyllite, (Mg,Fe)7(OH, Si4,O11)2, used for insulation products and construction materials, contaminant in chrysotile asbestos, vermiculite and talc.
Tremolite, Ca2Mg5(OH, F)2(Si4,O11)2, not used commercially, contaminants in chrysotile asbestos, vermiculite and talc.
Actinolite, Ca2(Mg, Fe2)5(Si8,O22)(OH,F)2, not used commercially, powdered mineral herbal medicine.

35.2.8 Augite
Augite (monoclinic, pyroxene, silicate), [(Ca, Mg, Fe2, Fe3, Ti, Al)2][(Si, Al)2O6]
Augite, Crystal systems, crystal habit, crystal form:35.8 (See 4. Monoclinic)
Augite, Silicates group, polysilicates, polysilicon:35.14.1 (See 3. Pyroxenes, MgSiO3, e.g. augite, jadeite, diopside).

35.2.46 Meerschaum
Meerschaum, H4Mg2Si3O10, is found as floating white lumps and was formerly used for tobacco pipes and holders.
It is a soft, light-coloured, hydrated magnesium silicate found in Asian Minor.
If newly dug up, it lathers like soap and has been used as soap.

35.2.31 Epsomite
Epsomite, hydrated Epsom salts, magnesium sulfate, bitter salt (kieserite), MgSO4.7H2O
It used as constipation medicine.
Periclase, MgO, magnesium oxide

35.2.10 Azurite
Azurite, 2CuCO3.Cu(OH)2, basic copper carbonate, basic copper carbonate, blue carbonate of copper, 2CuCO3.Cu(OH)2
Azurite has non-metallic vitreous lustre, Mohs scale of hardness 3.5-4, specific gravity 3.83, intense medium to dark azure blue colour, transparent to translucent, colourless streak.
Azurite (copper carbonate) habit of short tabular prisms, equidimensional plates, long spear-like crystals with pyramidal terminations.
The associated mineral is malachite, Cu2[(OH)2, CO3].

35.2.11 Bauxite
Bauxite, Al2O3 x2H2O, (hydrated aluminium oxide, Al2O3), is a residual sedimentary mineral.
It contains alumina and other oxides of aluminium in the amorphous or crystalline state.
So it is more a rock-like mixture than a mineral.
Bauxite is a mixture of iron and aluminium hydroxides and oxides.
It is usually formed by weathering in tropical regions.
It is the most important ore for production of aluminium.
Bauxite has non-metallic lustre, white streak, no good cleavage, can be scratched by the finger nail, white to brown grey colour, uneven fracture, specific gravity 2.0-2.5.

35.2.15 Bornite
Bornite, bournonite, Cu5FeS4
Bornite has purple to silver grey to black colour, Mohs scale of hardness 2.5-3, metallic lustre, black streak, poor cleavage, uneven to conchoidal fracture, and specific gravity 5.09.
It resembles gold or iron pyrite, but is more brittle than gold.
Bornite is called "cog wheel ore", because twinned crystals form in that shape.
Bornite may be a mixture of copper sulfides including Cu2S, (chalcocite) and CuS (covelite).
Note the twinning habit colour and density of the specimen.
Brookite, TiO2

35.2.19 Cassiterite
Cassiterite, tinstone, SnO2
Cassiterite has white to grey to black colour, with fractured pieces having brown colour, Mohs scale of hardness 1.5-2, white to grey streak, metallic lustre with the crystal faces often brilliantly shiny, cleavage poor, specific gravity 6.6 -7.15.
It is quite brittle, usually occurs in ancient granite rocks, e.g. pegmatite, as small veins crossing the granite, and forms twin crystals.
Note the density, colour and hardness of the specimen.

35.2.20 Cerussite
Cerussite, lead carbonate, PbCO3, ceruse, white lead ore
Cerussite has a non-metallic and adamantine lustre, Mohs scale of hardness 3-3.5, specific gravity 6.55, is colourless or white or grey, transparent to subtranslucent, but may be opaque white to wine yellow to brown-yellow to smoky brown, colourless streak.
It occurs as ore grade concentrations as a secondary mineral from the oxidized zones at Broken Hill where most of it is opaque white.
However, wine yellow, yellow brown, smoky brown, transparent and translucent examples occur.
It occurs as reticulated masses, complex arrowheads twinned crystals, and "jack straw" masses of tubular-shaped crystals.
It is found in ore bodies and is one of the most abundant minerals of the oxidized zone.
The associated minerals are malachite, [Cu2[(OH)2CO3], azurite, and bromian chlorargyrite.

35.2.22 Chalcopyrite
Chalcopyrite, CuFeS2, copper pyrite, copper iron sulfide, CuFeS2, has brassy yellow to green colour, but often tarnishes bronze or iridescent to form peacock ore, Mohs scale of hardness 3.5-4, dark green to black streak, metallic lustre, brittle, poor cleavage, conchoidal fracture and specific gravity 4.1-4.3, brittle and antiferromagnetic.
It is the main copper ore and is also a "fool's gold".
Copper pyrite resembles gold or pyrite, but it has a deeper brass colour and pyrite has Mohs scale of hardness 6-6.5.
Pyrite is more brittle than gold and weathers to form the secondary minerals limonite, malachite and azurite.
Chalcopyrite, copper iron sulfide, occurs in veins in garnet, quartzite and garnet sandstone in ore bodies.
The associated minerals are argentiferous galena and arsenopyrite, FeAsS.
It may become magnetic when heated.
Note the crystal habit and softness of the specimen.

35.2.23 Cinnabar
Cinnabar, HgS, mercuric sulfide, cinnabarite, quicksilver, HgS, mercuric sulfide (II) sulfide (calomel found with cinnabar), red crystals, native vermilion, China red, vermilion, is used for Chinese chops, and was used in old paintings, but is no longer used.
Cinnabar has brick red to scarlet colour, Mohs scale of hardness 2-2.5, red to scarlet streak, diamond-like lustre, but sometimes darker non-metallic lustre, uneven fracture, specific gravity 8.19.
It is the most important mercury ore and is linked with volcanic activity, dangerous medicine.
Calomel, mercury (I) chloride, is a similar mineral.
Note the density, cleavage and colour of the specimen.

Cadmium minerals
Cadmoselite, CdSe, cadmium (II) selenide
Cadmium sulfide, CdS, greenrockite
Greenockite, CdS, cadmium sulfide mineral
Hawleyite, CdS, cadmium sulfide mineral

35.2.17 Calomel
Calomel, mercury (I) chloride, Hg2Cl2, mercury (I) chloride, mercurous chloride, horn quicksilver, horn mercury, similar to cinnabar and found with it.
Note the density, cleavage and colour of the specimen.

35.2.25 Copper, Cu, natural copper
See: Copper (Chemistry)
See: Copper compounds, (Chemistry)
Copper has copper colour that tarnishes to green, copper red on a fresh surface, but usually dark, because of dark tarnish, metallic lustre, no cleavage, jagged fracture, copper red shiny streak, Mohs scale of hardness 2.5-3 and specific gravity 8.96.
The rare native copper, Cu, occurs as rounded branches often with green or blue spots.
Nowadays it occurs in mainly sulfide ores in veins or on the surface of crevices in sandstone, slates and igneous rocks.
Pure copper is malleable, ductile and can be cut into slices.
It has high thermal and electrical conductivity and resistance to corrosion so it is an excellent electrical conductor.
Copper combines with zinc to form brass and combines with tin to form bronze.
The name copper comes from the island of Cyprus. Copper, Cu, natural copper, has arborescent forms in large cavities, four-sided prisms, elongate octahedrons with repeated branches.
Also, stalactitic or dendritic masses in wire-like groups and nail head crystals.
Associated minerals are cuprite, Cu2O, red oxide of copper, and malachite, [Cu2[(OH)2, CO3] in weathering zone of copper deposits.
Note the colour, crystal form and ductility of a native copper specimen.
Covellite, copper sulfide mineral CuS
Cuprite, Cu2O, red oxides of copper
Turquoise, CuAl6[(OH)2, PO4]4.4H2O, callaite

Coprolites
Coprolites, fossilized animal dung

35.2.21 Chalcocite
Chalcocite, Cu2S, copper (II) sulfide, copper glance mineral, grey-black-blue, possibly iridescent, dark grey streak, Mohs scale of hardness 2.5-3, may be formed from other minerals, e.g. bornite, crystals almost hexagonal, igneous or metamorphic in copper deposits.

35.2.24 Coltan
See: Tantalum, Ta, Table of the elements
See: Niobium, Nb, Table of the elements
Coltan, "columbite-tantalite", Niobium and Tantalum metallic ore, from eastern Democratic Republic of Congo where "conflict tantalum" is mined by minors and adult workers under adverse conditions to cause genocides, heat resistant powder, tantalum holds charge well so is in smart phones, tablet computers and cell phones circuit boards, and its oxide in insulators.
High cost tantalum has been mined in Australia, Canada and Eritrea.

35.2.26 Coronadite
Coronadite, Pb2Mn8O16, (lead manganese oxide, formerly called psilomelane), occurs as massive, stalactitic, shawls, cellular, botryoidal habit, sub-metallic glossy to earthy lustre, Mohs scale of hardness 5-6, S.G. 5.53, colour black to brown black, streak brown black.
Coronadite (lead manganese oxide) originally referred to as psilomelane, is massive, stalactitic, shawls, cellular, botryoidal habit.
Abundant in the upper levels of the oxidized zone and outcrop with associated mineral goethite forms the matrix for secondary minerals.

35.2.27 Corundum
Corundum, Al2O3 + chromium, iron, titanium, Mohs scale of hardness 9, ruby, sapphire)
Aluminium oxide, Al2O3, (Chemistry)
Corundum as ruby contains Cr and is always red.
Sapphire contains Fe and Ti and is always blue-green, so a ruby is sometimes called a "red sapphire".

35.2.28 Cryolite
Cryolite, sodium aluminium fluoride, Na3AlF6
Cryolite has colourless to white to yellow colour, and sometimes purple to black colour, Mohs scale of hardness 2.5-3, white streak, greasy to glassy lustre, no cleavage, uneven fracture and specific gravity 2.95-3.0.
The refractive index is 1.34. so the specimen almost disappears in water.
It is a colourless rare mineral used as a flux in electrolytic production of aluminium from bauxite, and is manufactured synthetically.
Note the disappearance in water, no salty taste and density of the specimen.

35.2.30 Emery
Emery, corundite, is the naturally occurring mixture of the mineral corundum, magnetite and others, is very hard and is used as an abrasive both as powder or as blocks or wheels and in emery paper (like sandpaper).

35.2.32 Fluorspars
Fluorspar, CaF2 (fluorite, calcium fluoride, blue john, Derbyshire spar), has many colours, colourless if pure, but usually purple or green or yellow, depending on dissolved impurities, Mohs scale of hardness 4, white streak, glassy lustre, good cleavage in four directions, specific gravity 3.0-3.3.
Coloured specimens may fluoresce in ultraviolet light or glow when heated.
It occurs in veins in igneous rocks and can form twin crystals.
Large crystals have been carved into small vases.
It is used as a flux to smelt metals and to produce fluorine.
Flux, (Latin fluo to flow, because it melts at a low temperature).
Note colour, hardness, cleavage and possible fluorescence of the specimen.

35.2.33 Galena
Galena, PbS, lead glance, blue lead, silver grey to black colour, Mohs scale of hardness 2.5, lead grey streak, metallic lustre, good cleavage in four directions, and specific gravity 7.2-7.635.
It can mark paper and when hit with a hammer, breaks into perfectly cubic pieces, because of its cubic cleavage.
Tetraethyl lead [lead (IV) tetraethyl] was formerly used as an "anti-knock" agent in petrol (gasoline), but not now, because lead is toxic.
Lead is used in X-ray shields, lead cell accumulators, ammunition, fishing sinkers, solder and type metal.
Galena is the most important lead ore and is the main lead ore mineral at Broken Hill, Australia.
The silvery metallic lustre and cubic appearance characterize galena, density of 7.5.
Galena is the source of silver at Broken Hill, Australia, because silver atoms can substitute for lead atoms or be present within minerals such as acanthite (Ag2S) that have formed within galena.
Note the density, and cleavage in the specimen.

35.2.34 Goethite
Goethite, FeO(OH), hydrous iron oxide, needle iron ore, acicular iron ore, has adamantine to dull lustre, but silky in some fine, or scaly, or fibrous varieties, Mohs scale of hardness: 5-5.5, specific gravity 3.3-4.3, brown-yellow to dark brown colour, brown-yellow streak.
Limonite (brown iron ore, brown haematite, brown ironstone, is a cryptocrystalline mixture of mainly goethite, a weathering product of all iron deposits and in hydrothermal veins, with associated mineral coronadite.
It has a habit consisting of botryoidal, mamillary, stalactitic masses and crusts, and it is abundant in the gossanous capping of ore bodies.

35.2.35 Gold, Au
See: Gold (Chemistry)
Gold, E 175, has copper-yellow colour like butter, Mohs scale of hardness 2.5-3, gold to yellow streak, metallic lustre, no cleavage, jagged fracture, SG 19.3.
It is malleable, ductile and can be sliced.
Gold is a widely distributed metal and always occurs in a metallic state, generally as an alloy with silver, copper or iron.
It occurs in thin irregular hydrothermal veins in a quartz reef, placer deposits and conglomerates.
Gold does not tarnish, so it has been used as the universal standard of exchange.
Specks of gold can be separated by "panning" so that the greater weight of the gold causes it to settle, leaving the gravel at the surface.
The "white gold" used in jewellery and decorating pottery is usually an alloy of gold and nickel, but used in dentistry it is an alloy of gold and platinum.
Carat, (Gold)

35.2.36 Halite
Halite, rock salt, NaCl
See: Sodium chloride, (Chemistry)
Halite has colourless or white colour, Mohs scale of hardness 2, white streak, glassy lustre, good cleavage to break into cubes, conchoidal fracture, specific gravity 2.1-2.6.
The cubic crystals may have an indentation in one surface.
It forms from evaporation of sea water.
It may rise from deep layers to form massive salt domes and act as an oil trap.
Halite has a characteristic sharp taste.
The inland salt trade was once important for many places, e.g. Salzburg.
Table salt is always snowy white, but natural salt has many different colours, because of impurities.
A red colour is caused by ferric oxide (iron oxide), grey is caused by clay, and brown is caused by plant matter.
Used as table salt, road salt and glass manufacture.
In the Bible, Matthew 5: 13, "Ye are the salt of the earth: but if the salt have lost his savour, wherewith shall it be salted?
It is thenceforth good for nothing, but to be cast out, and to be trodden under foot of men."
Although pure sodium chloride cannot lose its saltiness, the rock salt used in biblical times often contained impurities.
If the sodium chloride content was leached away or lost by evaporation in very hot countries, the "salt" could indeed lose its salty taste.
Also, fine grain salt may taste saltier than coarse grain salt due to the greater surface to volume ratio so that more salt dissolve in the saliva and reach the taste receptors on the tongue.
The evaporates from sea water salt pans are not pure sodium chloride, because they may contain over 10% magnesium chloride to act as a desiccating agent and assist food preservation.
Note the cleavage at right angles and the taste of salt in the specimen.

35.2.37 Haematite
Haematite, Fe2O3, hematite, iron glance, specularite, antiferromagnetic.
Iron (III) oxide, Fe2O3, ferric oxide
Haematite has grey to black and red to brown colour, Mohs scale of hardness 5-6, red to brown streak, metallic to dull lustre, no cleavage, uneven fracture, specific gravity 5.26.
It is weakly magnetic.
The crystalline form is black and shiny.
It is an important iron ore and is used in paints as a pigment and in jeweller's rouge polish.
Haematite is antiferromagnetic, because the Fe crystallizes in a structure with oxygen ions, in an hexagonal close-packed framework in a plane, but it is antiferromagnetically coupled between the planes.
Antiferromagnetism occurs when the A and B sublattice moments are exactly equal, but opposite, so the net magnetic moment is zero.
Note the red to brown streak and hardness of the specimen.

35.2.38 Ilmenite
Ilmenite, FeTiO3, has black colour and gives a black powder as in "black sands", Mohs scale of hardness 5-6, brown to black streak, metallic lustre, no cleavage, conchoidal to uneven fracture, specific gravity 4.70-4.79.
Ilmenite is slightly magnetic.
The particles have been weathered from basic igneous rocks.
Note the density, lustre and streak of the specimen.
Iron minerals
Greigite, Fe3S4, iron (II, III) sulfide, mineral
Siderite, FeCO3, chalybite, spathose iron

35.2.39 Kaolinite
Kaolinite, Al2(OH)4(Si2, O5), Al4Si4O10(OH)8, known as white clay, pipe clay, ball clay and China clay, is used for making pottery.
Kaolinite, commonly potassium alum, is a combination of potassium and aluminium sulfates, Al2(SO4)3.K2(SO4).24H2O, KAl(SO4)2.11H2O.
It is a weathering product of feldspars, known as white clay, pipe clay, ball clay, Cornish clay and China clay, kaolin, (also dickite and nacrite minerals), is used in the manufacture of fine porcelain that is almost pure kaolin.
The cheaper grades are made with the addition of feldspar.
It is a soft white powder, insoluble in water, dilute acids or alkalis.
Kaolin clay contains mainly kaolinite and some illite.
Kaolin is ingredient of anti diarrhoea medicines to absorb bacteria and increase the bulk of faeces.
It is very astringent and is used for purifying water.
Soda alum or chrome alum are similar combinations where the potassium has been replaced by the corresponding metals.
Langbeinite, K2Mg2(SO4)3, may be in "potash fertilizers"

35.2.40 Kyanite
Kyanite, Al2(O, SiO4), disthene, munkrudite, cyanite, rhaeticite (white grey kyanite), (Greek kyanos blue), is an aluminosilicate mineral, Mohs scale of hardness 4-5 and 6.5-7 depending on the direction of the cleavage planes, colourless streak, vitreous lustre.
Found in aluminium-rich metamorphic pegmatites and sedimentary rock.
It is used in refractory and ceramic products, electrical insulators, abrasives, gemstones.
It has elongated, columnar crystals, and is anisotropic, i.e. two different harnesses on perpendicular axes.

35.2.41 Lapis lazuli
Lapis lazuli, ancient intense blue semi-precious stone, lazurite mineral, (Na, Ca)8[(S, Cl, SO4, OH)2.(Al6Si6O24)], original source of deep blue pigment ultramarine (beyond the sea), often occurs in crystalline marble, specific gravity 2.7-2.9.
This deep blue pigment much replaced after 1709 byPrussian blue.

35.2.42 Lead
See: Lead (Chemistry)
Lead, Pb, rarely occurs as the metal.
It has a metallic lustre, a dark grey colour and high specific gravity of 11.35.
Lead, Pb, occurs mainly as the lead ore galena (lead sulfide, PbS).
It is characterized by a metallic silver lustre and cubic fracture.
Cerussite (lead carbonate, PbCO3) and anglesite (lead sulfate, PbSO4) are found in areas where galena has been weathered or exposed to oxidizing groundwater.
Typically this occurred at or near the surface.
Lead was used in water pipes, roofing and pigments, but is now mostly used in batteries for vehicles and other equipment.
Crocoite, PbCrO4, red lead ore

35.2.43 Magnetite
Magnetite, Fe3O4, iron (II, III) oxide (FeO.Fe2O3), Fe²⁺Fe2³⁺O4
Magnetite nanoparticles, Ferrofluid (product on sale)
Iron oxide (black iron oxide), is a mixed base, Fe3O4
Magnetite (iron (II) diiron (III) oxide, magnetitum, ferrosoferric oxide, loadstone, triiron tetroxide, black magnetic iron oxide, ferrimagnetic magnetic lodestone, iron ore, black iron ore, black colour, Mohs scale of hardness 5.5 to 6.5, black streak, black powder, metallic to dull lustre, no cleavage, conchoidal fracture, cube-shaped crystals, specific gravity 5.17.
It is called magnetic iron ore and has magnetic properties unlike any other mineral.
Formerly, it was the strongest magnet known when known as lodestone, (Middle English lode way or journey, a stone that leads the way), which acts as a magnet when freely suspended, from Magnesia, in Greece, but magnetite is no longer used as a magnet, because much stronger and shaped magnets are needed.
It was probably first discovered in China where they used it for the first magnetic compasses.
Fragments of magnetite will be attracted to a magnet or will affect a suspended magnetic needle.
Magnetite has about 73% iron, but it may also contain magnesium, chromium and titanium.
Magnetite is widely distributed in igneous rocks and volcanic ashes so it is an important iron ore used in smelting.
Magnetite is a folk medicine for liver function and a sedative.
Magnetite is ferrimagnetic, not ferromagnetic, because it contains two magnetic sublattices, A and B, caused by the Fe ion surrounded by four oxygens and the Fe ion surrounded by six oxygens with uneven antiparallel spins on the sublattices, [Fe³⁺] sublattice A [Fe³⁺, Fe²⁺] sublattice BO4, to result in a net magnetic moment.
Some bacteria and the brains of bees and pigeons contain tiny magnetite crystals with perhaps a magnetic orientation function.
Note the magnetic property of the specimen and the streak.

35.2.44 Malachite
See: Copper (II) carbonate, (Chemistry)
Malachite, Cu2(OH)2CO3, or CuCO3.Cu(OH)2, copper (II) carbonate, has a non-metallic lustre, adamantine to vitreous in crystals that are often silky in fibrous varieties, dull lustre in earthy types, Mohs scale of hardness: 3.5 to 4, specific gravity 4.03, bright green and translucent or chalk-green to lush-green colour, pale green streak.
Malachite, copper carbonate, [Cu2[(OH)2CO3], has botryoidal and sometimes velvety habit.
It is found in ore bodies as powdery to compact fibrous crusts and hemispherical aggregates.
The associated minerals are azurite and cerussite.
This greenish rock could be put in a very hot fire to yield copper, an important process in the history of metal technology, about 5000 BC, which signified the end of the Stone Age.

35.2.45 Marcasite
Marcasite, iron sulfide, FeS2, spear pyrites
Marcasite has brass to yellow colour with a green tinge, Mohs scale of hardness 6.5, green to black streak, metallic lustre, poor cleavage, uneven fracture, and specific gravity 4.88.
So it is similar to pyrite, but has radiating groups of twin crystals like a cock's comb.
Old specimens may oxidize to give off sulfur in an exothermic reaction.
Note the crystal habit of the specimen and compare the specimen with pyrite.
An old specimen may have a sulfur smell.

Mascagnite, ammonium sulfate crystals in white to yellow stalactite-like masses, soft, water soluble, good cleavage

35.2.47 Mercury, Hg
See: Mercury (Chemistry)
Mercury, Hg, is a bright silvery coloured liquid that forms spherical droplets if spilt.
The relative specific gravity is 13.6.
Mercury was formerly called quicksilver and is the only metal that is liquid at room temperatures.
It rarely occurs free in rock cavities.
Mercury is used in thermometers, barometers, dental amalgams, silver-plating of mirrors and to separate gold from silver.
Note the appearance and movement of mercury in a mercury thermometer.
Do not allow students to touch mercury or to have any access to free surface metallic mercury.

35.2.77 Millerite
Millerite, NiS, nickel sulfide, hair pyrites, has brass to yellow colour, Mohs scale of hardness 3 to 3.5, green to black streak, metallic lustre, cleavage in 3 directions, but not obvious in thin crystals, and specific gravity 5.3-5.5.
It forms thin, needle-like crystals called "hair nickel" with a bright metallic lustre.
It occurs in iron-nickel meteorites.
Note the crystal habit, colour and lustre of the specimen.

35.2.48 Molybdenite
Molybdenite, molybdic ochre, MoS2, has silvery grey to black metallic colour with a blue tinge, powder has the same colour as the crystal, Mohs scale of hardness 1-1.5, blue to grey streak, can mark paper, good platy cleavage that forms flakes and specific gravity 5.0.
Molybdenum, Mo, occurs as branches in pipes of quartz, but is one of the less common metallic elements.
The main use of this metal is in making blue pigment in glasses.
Because molybdenite resists repeated shocks, it is added to steel to improve its strength and toughness.
Note the greasy feel, the marks left on the fingers, and the blue streak of the specimen.
Molybdite, molybdenum ochre, MoO2

Monazite, reddish phosphate rare mineral (Ce, La, Nd, Th)(PO4.SiO4)

35.2.49 Nacre
Nacre, CaCO3, mother of pearl, specific gravity 2.68-2.86, pearls, an inner shell layer of some molluscs, is iridescent, because of tiny plates of aragonite held within an organic matrix, e.g. chitin, that strengthens the nacre.
It may produce a blister pearl attached to the interior of the shell, or a free pearl within the mantle tissues.
Glauberite, brongniartite, Na2SO4, CaSO4
Nahcolite
Nahcolite, NaHCO3, thermokalite, sodium hydrogen carbonate mineral, in evaporates
Natron
Natron, Na2CO3.10H2O (+ some NaHCO3 + NaCl, sodium carbonate decahydrate), in saline lake beds

35.2.50 Nickel, Ni
See: Nickel (Chemistry)
Nickel is blue to white colour, Mohs scale of hardness 3.5, grey metallic streak, metallic lustre, no cleavage, specific gravity 8.9.
Native nickel is rare, but it occurs in iron meteorites and in many different minerals, often oxidized to form green nickel "blooms", hydrated nickel salts.
Nickel is weakly magnetic and malleable.
Note the weak attraction to magnets and density of the specimen.

35.2.51 Nickeline
Nickeline, niccolite, NiAs, arsenical nickel has copper red colour with a red tinge, Mohs scale of hardness 5 to 5.5, brown to black streak, metallic lustre, uneven fracture, specific gravity 7.8, occurs in masses.
The name "nickel" comes from "Old Nick" (the devil) meaning it was worthless as a copper ore despite its similar colour.
Nickel is used for kitchen vessels, nickel electroplating and tougher nickel steel for armour plating and machinery parts.
An alloy of copper, zinc and nickel is called "German silver".
An applied magnetic field causes nickel to decrease in length so nickel wire may be used in some types of computers.
Note the colour, density, streak and sometimes an odour when heated.

35.2.53 Palagonite
Palagonite, mafic volcanic glass, altered by hydration of siderolemane or thrachylite.
Rock mineral fertilizer dust containing high levels of Si, Ca and trace minerals, used in compost-making and soil mixes.
It holds water well so is used in sandy soils.

35.2.54 Platinum, Pt
See: Platinum (Chemistry)
Platinum has steel grey colour of native platinum, but silver-white colour of pure metal, Mohs scale of hardness 4 to 5.5, steel grey streak, metallic lustre, no cleavage, jagged fracture, specific gravity 14-19
Platinum does not react with air, water or strong acids (except a mixture of hydrochloric acid and nitric acid).
Native platinum is very rare and occurs in alluvial deposits as scales and grains or cubic crystals.
Note the density, colour and hardness of the specimen.

35.2.55 Pyrite
Pyrite, iron pyrite, iron sulfide, FeS2 : See: Iron (II) sulfide (Chemistry)
Iron sulfide, FeS2, iron disulfide, sulfuric pyrites, pyrite, iron pyrites, fool's gold, marcasite
Pyrite has pale brass yellow colour, Mohs scale of hardness 6 to 6.5, black green to black brown streak, but green or brown to black powder, metallic lustre, poor cleavage, conchoidal to uneven fracture, and specific gravity 4.9-5.2.
It is the most common sulfide mineral and occurs as cubic crystals.
It is found in lining cavities in faults and fractures in ore bodies.
The associated minerals are calcite and rhodocrosite.
It gives out sparks when struck with steel, because of the fragments of sulfur igniting.
Pyrite was used in the old wheel lock firearms to produce the spark to explode the gunpowder.
Pyrite frequently shows traces of gold, silver, copper, nickel and arsenic.
It can occur in mineral veins where it was commonly mistaken for gold, "fool's gold", but it may be rich in gold or copper or sulfur.
It is used to manufacture sulfuric acid, but is not smelted for iron production.
Pyrite may be polished and used in jewellery, but it is not malleable.
Pyrite may have characteristic striations on the surfaces of the crystal faces.
Pyrite, iron sulfide, is found in lining cavities in faults and fractures in ore bodies.
The associated minerals are calcite and rhodocrosite.
Pyrite is not magnetic, but is attracted to a magnet.
Pyrite can be used in solar cells instead of silica.
Pyrite crystals were used as crystal detectors in "crystal set" radio receivers.
Note the hardness, streak and lustre of the specimen.

35.2.56 Pyromorphite
Pyromorphite, Pb5Cl(PO4)3, has non-metallic and resinous to adamantine lustre, Mohs scale of hardness: 3.5-4, and colour consisting of shades of green, yellow, brown, grey and yellow-orange, sub transparent to translucent, specific gravity 6.5-7.1, colourless streak.
Pyromorphite is the most common lead phosphate, lead chlorophosphate.
It is a secondary mineral from the oxidized zone.
It has a large range of habits and colours including coatings and sprays, simple hexagonal prisms, stout hexagonal prisms, branching aggregates, mamillated, botryoidal and colloform masses.
It is found all along the lode outcrop.
The associated minerals are coronadite, cerussite, secondary galena, and anglesite.

35.2.57 Pyrrhotite
Pyrrhotite, FeS, iron sulfide, has metallic lustre, Mohs scale of hardness 4, specific gravity 4.58-4.65, brown-bronze colour, black streak.
It is found in veins, zones and bands in ore bodies.
Pyrrhotite can be weakly magnetic, but not at Broken Hill, where the associated minerals are calcite, galena, and chalcopyrite.

35.2.58 Rhodochrosite
Rhodochrosite, manganese carbonate, MnCO3, is a pink mineral found in fault zones along with other carbonate minerals, e.g. calcite.

35.2.59 Rhodonite
Rhodonite, manganese silicate, MnSiO3, or ([Mn, Ca]SiO3), specific gravity 3.69, is the most abundant manganese mineral found in the galena-rich ore bodies.
It has a range of beautiful red pink "rosy" colours.
Hausmannite, manganese (II, III) oxide, Mn3O4, manganese tetroxide, insoluble in water, soluble in HCl

35.2.60 Rutile
Rutile, TiO2, titanium (IV) oxide, TiO2, titanium dioxide, nanopowder, fine powder, Anatase mineral, toxic if inhaled
Titanium (IV) oxide, powder, TiO2, titanium dioxide, colour white, opacifer, "white out" correction fluid, white pigments for tennis shoes, household white paint, from mineral rutile, ilmenite FeTiO3, food additive, E171, the three mineral forms are anatase, brookite and rutile.
Rutile (titanium (IV) oxide, titanium dioxide, titania), has black or yellow to red to orange colour, Mohs scale of hardness 6-6.5, brown streak, diamond-like lustre, good cleavage in two directions, conchoidal to uneven fracture, specific gravity 4.25.
Titanium is used in the aerospace industry to produce low density corrosion resistant steels.
Titanium dioxide has replaced lead in lead paint.
Titanium forms a protective layer in air, a passive oxide coating.
Note the lustre, hardness and streak of the specimen.
Sagenite, TiO2, mineral

35.2.61 Scheelite
Scheelite crystals, calcium tungstate, CaWO4, has white to orange to grey colour, Mohs scale of hardness 4.5-5, white streak, diamond-like to greasy lustre, poor cleavage, conchoidal to even fracture, and specific gravity 5.9-6.1.
The crystals are usually not water worn, so they keep their characteristic pyramid shape.
They are transparent to translucent and may be bright or dull, with rough surfaces.
It fluoresces blue in ultraviolet light.
This mineral occurs in veins in granite rocks with cassiterite or fluorspar.
Scheelite is an important ore of tungsten.
It was used to increase the hardness of steel.
Note the crystal habit, fluorescence, and lustre of the specimen.

35.2.62 Silver, Ag
See: Silver (Chemistry)
Silver has silver white shiny colour that tarnishes to a black colour, Mohs scale of hardness 2.5-3, silver to white streak, metallic lustre, no cleavage, jagged fracture, and specific gravity 10.5, if pure, but 10-12 if impure.
It is malleable and ductile, can be cut into slices, and is one of the best conductors of electricity.
It is a precious metal ranked next to gold and was once obtained from natural large masses, but now is a by-product from the refining of lead, zinc, copper and gold.
Silver can be moulded and shaped to form jewellery, because of its pure white colour, softness and toughness.
Silver has massive, wire habit.
The associated minerals are gold and copper.
Silver occurs in a variety of minerals, but most of the silver is found as trace amounts of silver mineral locked up inside the lead mineral, galena.
Sometimes silver occurs as big lumps, nuggets, of the metal itself.
Only silver ever comes out of the ground as a metal.
Lead and zinc are always locked away minerals, as is most of the silver.
Silver was largely used in the photographic industry although it has uses in jewellery, electronics and silverware.
Note the colour and tarnish of the specimen.
Kerargyrite, AgCl, horn silver

35.2.63 Smithsonite
Smithsonite, ZnCO3 (basic zinc carbonate, ZnCO3.2ZnO.3H2O), calamine, zinc spar, galmei, a non-metallic and vitreous to waxy lustre, Mohs scale of hardness 4-4.5, specific gravity 4.4-4.5, colourless to white to green to pink to blue colour, colourless streak.
It is used as the main ingredient in zinc sun cream.
Calamine, is used in pink calamine lotion for treating sunburn.
Smithsonite, zinc carbonate, ZnCO3, is a widespread secondary mineral from the oxidized zones.
It occurs as rounded botryoidal aggregates resembling drops of wax and as honeycombed masses in ore bodies.
It is the most abundant secondary carbonate after cerussite.
The associated minerals are coronadite and goethite.
It is a widespread secondary mineral from the oxidized zones.
The associated minerals are coronadite and goethite.
It was formerly used to produce brass.
Calamine, Zinc carbonate, ZnCO3, harmful if ingested, calamine, zinc spar, smithsonite
Note the colour and colourless streak.
Spodumene
Spodumene, LiAlSi2O6, lithium aluminium silicate, forms 6 m crystals, grey-white ash when is ignited.

35.2.64 Sphalerite
Sphalerite, ZnS:See: Zincsulfide (Chemistry)
Sphalerite, zinc sulfide, zinc blende, blende, mock ore, mock lead, black jack, zinc iron sulfide (Zn, Fe)S, has black colour, but other colours also occur, Mohs scale of hardness 3.5-4, yellow to brown streak, diamond-like to submetallic lustre, good cleavage in 6 directions, specific gravity 3.9-4.1.
The crystals may be transparent with brilliant sheen or translucent to opaque with metallic lustre.
It may glow if crushed, triboluminescent.
Zinc blende frequently occurs in compact masses with quartz, copper pyrites and galena.
Zinc is used to galvanize iron for roofing, for lining iron "tins" to prevent rust and in the manufacture of white paint and optical glass.
Sphalerite (zinc sulfide, ZnS) is the main zinc ore mineral at Broken Hill.
Good crystalline sphalerite is unusual at Broken Hill.
The colour of sphalerite varies with its impurities.
At Broken Hill it is black, but some rare large crystals have a deep red colour.
Note lustre, streak and softness of the specimen.

Sodalite
Sodalite, Na8(Al6Si6O24)Cl2, igneous, plutonic mineral, changes colour in sunlight, used in self-adjusting sunglasses
Spinel
Spinel, Al2MgO4, MgAl2O, (Latin spinella pointed crystals) hardness 8, specific gravity 3.5 to 4.1, many different colours gemstone recently sold for 962.500 GBP, hardness is 8, its specific gravity is 3.5–4.1, in igneous periditite, found in Tajikistan.

35.2.65 Stibnite
Stibnite, Sb2S3, antimonite, antimony glance, grey antimony
Stibnite, has grey to silver colour, Mohs scale of hardness 2, dark grey streak, metallic lustre, cleavage in one direction and specific gravity 35.6.
Stibnite can mark paper, the crystals are curved and twisted, and it is the most important source of antimony, an important metal in the printing industry.
Note the crystal habit of the specimen.
Valentinite, Sb2O3, antimony bloom

35.2.66 Stilbite
Member of the zeolite group, lamellar zeolite, hydrated sodium calcium aluminium silicate, Ca(Al2Si7O18).6H2O.
Stilbite, hydrated sodium calcium aluminium silicate, has more than one chemical formula, e.g. Na2CaK2Al2Si7O18.7H2O, or NaCa2Al5Si13O3614H2O, has white to pink to yellow colour, Mohs scale of hardness 3.5-4, white streak, glassy to pearly lustre, good cleavage in one direction, specific gravity 4.56.
Note how thin crystals stick together like a sheaf of wheat, lustre and density of the specimen.

Strontium minerals
Celestine, SrSO4
Strontianite, SrCO3, strontium carbonate

35.2.104 Sulfur
Sulfur, S, has yellow crystals with colour sometimes masked by impurities, Mohs scale of hardness 2, yellow streak, glassy lustre, poor cleavage, conchoidal fracture, and specific gravity 2.07 (rhombic).
If held in a warm hand it may crackle, so it should be handled with care.
It burns with a small blue flame to form sulfur dioxide.
It is given off from volcanoes and deposited by the waters of some geysers and hot springs.
Sulfur is used in the manufacture of sulfuric acid, insecticides, medicines, matches, gunpowder and fireworks.
Note the colour, smell, and sensitivity to heat of the specimen.

35.2.67 Tanzanite
Tanzanite is found near Mount Kilimanjaro, Tanzania, specific gravity 3.25-3.60.
It is a variety of the mineral zoisite (Ca2)(Al3)(Si2O7)(SiO4)O(OH), that has been artificially heated to become a gemstone, which exhibits trichroism, i.e. alternately sapphire blue, violet, and burgundy colours, depending on crystal orientation.

Tellurium
Tellurium, Te, natural tellurium, rare metalloid, gas dimethyl telluride, (CH3)2Te, smells like garlic

Thorite
Thorite, ThSiO4, Thorite, (Th,U)SiO4, horium mineral, uranium ore

35.2.68 Tin
Tin, Sn, is very rare as native tin in placer deposits and tin is seldom used by itself.
Specific gravity 7.28.
Bronze is approximately 5% tin and 95% copper.
Other tin alloys include solder and pewter.
Tin is used in the glass industry.

35.2.69 Uraninite
Uraninite, UO2 (with UO3, Th, Pb, pitchblende, pitch ore), occurs usually as pitch-like masses (not crystals), has dull grey to black colour with brown tint, Mohs scale of hardness 5-6, brown to black streak, metallic to dull lustre or a shine like pitch, poor cleavage, conchoidal to uneven fracture, and specific gravity 8-10.6.
It is moderately hard and very heavy.
It undergoes radioactive decay to produce radium and helium, and other decay products.
Uranium is used in high grades of steel and is also the basic material used in atomic bombs and the world's nuclear power stations.
It is a rare material, but large deposits occur.
Note the radioactivity, lustre, colour and streak of the specimen.

35.2.70 Uranium, U
Uranium (Chemistry)
1. Uranium occurs as uranium dioxide, UO2, in the mineral pitchblende, uraninite, that also contains radium and products of radioactive disintegration.
Uranium ores usually contain: Actinium.
2. Natural uranium is about 0.72% U235 (atomic number 92 + 143 neutrons) and 99.28% U238 (atomic number 92 + 146 neutrons).
The half life of U235 is smaller than the half life of U238, specific gravity 19.05.
The uranium decay series involves 14 steps as uranium decays eventually into lead.
3. Uranium fission is a nuclear reaction used to produce energy by neutron bombardment to form krypton-89 and barium-144 and 3 neutrons that can start a chain reaction.
The heat and radiation from the chain reaction must be controlled only by controlling the chain reaction.
²³⁵U92 + ¹n0 --> ⁸⁹Kr36 + ¹⁴⁴Ba56 + 3¹n0 + λ
uranium-235 + neutron --> krypton-89 + barium-144 + 3 neutrons + radioactive decay constant
4. Uranium-238 spontaneously decays, first by alpha particle emission, alpha radiation (α radiation).
²³⁸U92 --> ²³⁴Th90 + ⁴He2 + γ
An alpha particle can be shown as ⁴He2 or⁴α2.
uranium-238 --> thorium-234 + alpha particle + gamma rays
Uranium-238 eventually decays by 14 steps to ²⁰⁶Pb82.
Lead is more stable than the previous radioactive elements in the decay series.

35.2.71 Wolframite
Wolframite, iron manganese tungstate (Fe, Mn)WO4, has grey to brown to black colour, Mohs scale of hardness 4-4.5, brown to black streak, dull lustre, good cleavage in one direction, specific gravity 7.0-7.5.
Wolframite is an important ore of tungsten, W, used to increase the hardness of steel.
Note the cleavage, density and lustre of the specimen.

35.2.72 Zeolite
Zeolite (T5O10, T10O20 chains), e.g. tetrapropylammonium (TPA) ZSM-5, clinoptilolite
Zeolite, e.g. tetrapropylammonium (TPA)ZSM-5, is a group of natural or synthetic hydrated aluminium silicates that appear to boil when heated in a blowpipe, specific gravity 2.0-2.4.
They retain pores or channels in their crystal structure, easily gain or lose water, and have a high ion exchange capacity.
Zeolites are used in detergents as water softeners, and as catalysts for reforming petroleum products.
Zeolites are used in PSAOxygen concentrators
Sodium aluminosilicates, e.g. albite (NaAlSi3O8), jadeite (NaAlSi2O6), "Zeolite A", synthetic laundry detergent, Na12Al12Si12O48. 27H2O

35.2.73 Zinc
See: Zinc (Chemistry)
Zinc, Zn, is white to blue grey colour, grey streak, metallic lustre, good cleavage in one direction, specific gravity 7.1.
It almost never occurs as the metal, but combined with sulfur or oxygen.
Zinc is brittle and must be heated to become malleable or ductile.
Zinc occurs mainly as sphalerite (zinc sulfide, ZnS).
At Broken Hill it has a black resinous appearance, but rarely shows as big crystals.
Smithsonite (zinc carbonate, ZnCO3), caused by weathering and oxidation of ore by groundwater, is found in areas where the ore body was at or near the surface.
Zinc is used in galvanized coatings of iron and steel.
It is also used in die cast alloy products, pigments and other industrial and agricultural applications.
Note colour, hardness and density of the specimen.

35.2.74 Zincite
Zincite, red oxide of zinc, ZnO, is found in metamorphic weathered deposits, specific gravity 5.66.
Adamite, Zn2(AsO4)(OH)
Hydrozincite, Zn5(CO3)2(OH)6, zinc bloom