Mineral Groups

All others: 1.5%

Element Abundances

Silica(SiO4)4-SILICATES

Common cations thatbond with silica anions

Mineral Groups

FerromagnesianSilicates (Fe, Mg)

Non-ferromagnesianSilicates (K, Na, Ca, Al)

OxidesCarbonatesSulfides/sulfatesNative elements

Mineral Groups

Actinolite (Tremolite) Ca2(Mg,Fe)5Si8O22(OH)2Subclass: Amphibole Streak: White Hardness: 5 – 6 Lustre: Vitreous Density: 3.0 - 3.4Habit: Aggregate of acicular grainsColours: Greenish - white

Crystal System: MonoclinicCleavage: UnevenFracture: SubconchoidalMagnetism: NoneReaction with HCl: None

Identification in hand sample:Habit and colour are best indicators.

Associations:Metamorphosed calcareous sediments

Comments:Higher in Fe than tremolite.

Silicates

Antigorite (Serpentine) Mg3Si2O5(OH)4 Subclass: PhyllosilicateHardness: 2.5 - 3.5 Streak: White Density: 2.6 Lustre: Greasy or waxy Habit: Lath-shaped crystals.Colours: Shades of green

Crystal System: MonoclinicCleavage: Perfect basalFracture: Splintery or conchoidalMagnetism: NoneReaction with HCl: Unknown

Identification in hand sample:Lustre, colour and habit are indicative.

Associations:Formed by hydrothermal action of mafics and ultramafics. Associations may include talc, calcite, brucite, chlorite, magnetite and chromite.

Silicates

Augite (Ca,Na)(Mg,Fe,Al,Ti)(SiAl)2O6Subclass: PyroxeneHardness: 5.5 – 6 Streak: White or gray Density: 3.2 - 3.5 Lustre: Vitreous Habit: Small blocky grains.Colours: Dark-greeny black colour

Crystal System: MonoclinicCleavage: Good / UnevenFracture: Uneven to conchoidalMagnetism: NoneReaction with HCl: None

Identification in hand sample:Colour, cleavage and hardness are indicative of a pyroxene. Augite has 2 cleavage planes at 90°.

Associations:Found in mafic to ultramafic rocks, and in high-grade metamorphs.

Industrial / ecomonic uses:None.

Silicates

Biotite K(Mg,Fe)3(AlSi3O10)(OH)2Subclass: PhyllosilicateHardness: 2 – 3 Streak: Colourless Density: 2.7 - 3.4 Lustre: Vitreous Habit: MicaceousColours: Brown, black, reddish brown

Crystal System: MonoclinicCleavage: Perfect basalFracture: UnevenMagnetism: NoneReaction with HCl: Very weak

Identification in hand sample:Colour and habit

Associations:A very common mineral found in igneous, metamorphic and sedimentary rocks.

Industrial / ecomonic uses:Altered into vermiculite, biotite is used as an insulation material and as filler in certain building supplies.

Silicates

Chalcedony (Micro/Cryptocrystalline Quartz) -- SiO2Subclass: FrameworkHardness: 7 Streak: White Density: 2.7 Lustre: Vitreous / almost waxy Habit: Aggregate of very tiny SiO2 grains.Colours: White/gray or any colour

Crystal System: HexagonalCleavage: NoneFracture: ConchoidalMagnetism: NoneReaction with HCl: None

Identification in hand sample:Identified by hardness and texture/habit.

Associations:Abundant in felsic rocks.

Industrial / ecomonic uses:Used for making glass and as a source of Silicon.

Silicates

Chlorite (Mg,Fe,Al)3(Si,Al)4O10(OH)2Subclass: PhyllosilicateHardness: 2 - 2.5 Streak: Greenish white to white Density: 2.6 - 3.3 Lustre: Vitreous to somewhat pearly, waxy, dull Colours: Greenish-black (typical)

Crystal System: MonoclinicCleavage: Perfect {001}Magnetism: NoneReaction with HCl: None

Identification in hand sample:Colour and its low hardness are distinguishing characteristics.

Industrial / ecomonic uses:None, however chlorite schist sometimes does have ornamental uses.

Silicates

Chrysotile (Serpentine) Mg3Si2O5(OH)4Subclass: PhyllosilicateHardness: 2.5 Streak: White Density: 2.5 Lustre: Silky Habit: FibrousColours: Shades of green

Crystal System: MonoclinicCleavage: NoneFracture: UnevenMagnetism: NoneReaction with HCl: Unknown

Identification in hand sample:Habit and colour and most indicative properties.

Associations:Found by hydrothermal alteration of mafics and ultramafics. Associated with talc, calcite, brucite, chlorite, magnetite and chromite.

Industrial / ecomonic uses:Used in 98% of world's production of asbestos.

Silicates

Epidote Ca2(Fe,Al)3(SiO4)3(OH) Subclass: SorosilicateHardness: 6 – 7 Streak: White Density: 3.4 - 3.5 Lustre: Vitreous Habit: Aggregate of small grains, striated faces, small but visible crystalsColours: Greeny, yellow-green, black

Crystal System: MonoclinicCleavage: PerfectFracture: UnevenMagnetism: NoneReaction with HCl: None

Identification in hand sample:Slight colour difference between this mineral and olivine, but only under magnification (where details in the crystals can be seen). Also indicitive is the presence of a cleavage plane.

Associations:Common accessory mineral in many regional and contact metamorphed rocks, particularly in more iron-rich rocks.

Industrial / ecomonic uses:Semiprecious gemstone

Silicates

Garnet (Pyrope, Grossular, Almandine)(Mg,Fe,Ca)3Al2(SiO4)3

Hardness: 6.5 – 7 Streak: White Density: 3.8 Lustre: Vitreous Habit: Small, well-formed crystalsColours: Darker reddy colours

Crystal System: IsometricCleavage: NoneFracture: ConchoidalMagnetism: NoneReaction with HCl: None

Identification in hand sample:Crystal habit, colour and hardness.

Industrial / ecomonic uses:Abrasives (particularly sandpaper), semi-precious gemstone.

Silicates

HornblendeCa2(Mg,Fe)4Al(Si7Al)O22(OH,F)2

Subclass: AmphiboleHardness: 5 – 6 Streak: White or gray Density: 3.3 - 3.4 Lustre: Vitreous Habit: Intergrown crystals, prismatic character of grains.Colours: Black

Crystal System: MonoclinicCleavage: 2 at 56° and 124°Fracture: Uneven / conchoidalMagnetism: NoneReaction with HCl: None

Identification in hand sample:Prominent striations, prismatic crystals and angle on cleavages is distinguishing.

Associations:Forms in igneous rocks, and in the metamorphic rock amphibolite.

Industrial / ecomonic uses: Ornamental.

Silicates

Muscovite KAl2(AlSi3O10)(OH)2Subclass: PhyllosilicateHardness: 2.5 – 4 Streak: Colourless Density: 2.8 - 2.9 Lustre: Vitreous Habit: MicaceousColours: Colourless, to white or gray

Crystal System: MonoclinicCleavage: Perfect basalFracture: UnevenMagnetism: NoneReaction with HCl: None

Identification in hand sample:Colour and habit are best indicators.

Industrial / ecomonic uses:Used in the electronics industry in the manufacture of capacitors, transistors, insulators and certain window types. Also used as a filler in building materials.

Silicates

Olivine (Forsterite (Mg) and Fayalite (Fe))Mg2SiO4 - Fe2SiO4Subclass: NesosilicateHardness: 6.5 – 7 Streak: Colourless Density: 3.3 - 4.3 Lustre: Vitreous Habit: GranularColours: Pistachio green, greenish yellow brown

Crystal System: OrthorhombicCleavage: ImperfectFracture: ConchoidalMagnetism: NoneReaction with HCl: Very weak

Identification in hand sample:Pistachio-green colour and granular habit.

Associations:Mafic and ultramafic igneous rocks. Associated with Ca-plag,

Industrial / ecomonic uses:Peridote (a translucent variety of olivine) is considered a 'gem' mineral. Also used as a refractory sand and infrequently as an abrasive.

Silicates

Orthoclase KAlSi3O8Hardness: 6 - 6.5 Streak: White Density: 2.6 Lustre: Vitreous Habit: Polysynthetic twinningColours: Pinky-white

Crystal System: OrthorhombicCleavage: PerfectFracture: SubconchoidalMagnetism: NoneReaction with HCl: None

Identification in hand sample:Colour and evidence of exsolution with plagioclase.

Associations:Very common in granite, granodiorite, syenite and related felsic rocks.

Silicates

Quartz (crystal) SiO2

Hardness: 7 Lustre: Vitreous / glassy Density: 2.7 Habit: Crystalline Colours: Clear transparent

Crystal System: HexagonalCleavage: NoneFracture: ConchoidalMagnetism: NoneReaction with HCl: None

Identification in hand sample:Hardness, translucency and colour are indicators.

Silicates

Talc Mg3Si4O10(OH)2Subclass: PhyllosilicateHardness: 1 Streak: White Density: 2.6 - 2.8 Lustre: Greasy Habit: Compact masses, often no crystals.Colours: White, or brownish, dark green, gray

Crystal System: MonoclinicCleavage: PerfectFracture: UnevenMagnetism: NoneReaction with HCl: Unknown

Identification in hand sample:Mineral is very soft and are often compact masses. Colour is typical and varies to brown, green or gray.

Silicates

Topaz Al2SiO4(F,OH)2Hardness: 8 Streak: White Density: 3.5 Lustre: GlassyHabit: Prismatic crystalsColours: Almost brownish, any colour

Crystal System: OrthorhombicCleavage: PerfectFracture: SubconchoidalMagnetism: NoneReaction with HCl: None

Identification in hand sample:Resembles quartz, but harder.

Associations:Quartz

Industrial / ecomonic uses:Gemstone

Silicates

Zircon (ZrSiO4) Hardness: 7.5 Streak: White Density: 4.6 - 4.7 Lustre: Subadamantine Habit: Excellent tetragonal prismsColours: Colorless, red, brown, yellow, green or gray

Crystal System: TetragonalCleavage: ImperfectFracture: ConchoidalMagnetism: NoneReaction with HCl: Unknown

Identification in hand sample:Excellent crystalline habit, density and streak/colour are indicative.

Industrial / ecomonic uses:Source of zirconium and hafnium

Silicates

Azurite ---Cu3(CO3)2(OH)2Hardness: 3.5 – 4 Streak: Lighter blue Density: 3.8 Lustre: Vitreous, earthy (fine grained) Habit: Fine grained coating or fracture filling on rockColours: Azure blue

Crystal System: MonoclinicCleavage: PerfectFracture: ConchoidalMagnetism: NoneReaction with HCl: Strong

Identification in hand sample:Colour is reliable, association with malachite is also indicative.

Associations:Common mineral in the near-surface oxidized portion of copper-bearing hydrothermal sulfide mineral deposits. Associated with malachite.

Industrial / ecomonic uses:A minor ore of copper, also has ornamental uses. Sometimes a pigment (when powdered).

Carbonates

Aragonite ----CaCO3

Hardness: 3.5 – 4 Lustre: VitreousStreak: White Habit: Stalactitic aggregate of crystals or grains.Colours: Colourless or white

Crystal System: OrthorhombicCleavage: PinacoidalFracture: SubconchoidalMagnetism: NoneReaction with HCl: Strong

Identification in hand sample:Stalactitic habit, hardness (greater than that of calcite) and colour.

Associations:Occurs in carbonate-bearing blueschist metamorphic rocks. Associated with glaucophane, lawsonite, pumpellyite. Also forms at or near the surface in cave and hot spring deposits.

Industrial / ecomonic uses:Same as calcite, however abundance is much much less than that of calcite, thus having little economic value.

Carbonates

Calcite (massive) CaCO3Hardness: 3 Density: 2.7Streak: White Lustre: VitreousHabit: Fine grained aggregates (massive)Colours: Colourless, white, gray, yellow-brown, pink, rose red

Crystal System: HexagonalCleavage: Perfect rhombohedralFracture: SubconchoidalMagnetism: NoneReaction with HCl: Strong

Identification in hand sample:Recognized by hardness and cleavage. Dolomite and aragonite have higher densities.

Associations:Common as a cementing agent in clastic sediments, or as fossil fragments. Essential constituent of limestone.

Industrial / ecomonic uses:Used in the manufacture of portland cement (quicklime). Also used as a pharmaceutical (antacids, calcium supplements).

Carbonates

Calcite (sparry) (Iceland Spar) ---- CaCO3Hardness: 3 Streak: WhiteDensity: 2.7 Lustre: Vitreous Habit: Large crystals, some exhibiting common twin striaeColours: White

Crystal System: HexagonalCleavage: Perfect rhombohedralFracture: SubconchoidalMagnetism: NoneReaction with HCl: Strong

Identification in hand sample:Hardness, crystal habit and twin striae are typical.

Associations:Common as a cementing agent in clastic sediments or as fossil fragments.

Industrial / ecomonic uses:Used in the manufacture of portland cement (quicklime) and in the pharmaceutical industry.

Comments:The transparent variety is called "Iceland Spar".

Carbonates

Dolomite ---- CaMg(CO3)2Hardness: 3.5 – 4 Streak: WhiteDensity: 2.85 Lustre: VitreousHabit: Crystalline or aggregate, some with twin striae.Colours: Pinky/peach, white, gray, brown.

Crystal System: HexagonalCleavage: Perfect rhombohedralFracture: SubconchoidalMagnetism: NoneReaction with HCl: Weak

Identification in hand sample:Harder than calcite

Associations:Major constituent of dolostone (aka dolomite).

Industrial / ecomonic uses:Used in manufacture of portland cement.

Carbonates

Malachite ---- Cu2(CO)3(OH)2Hardness: 3.5 – 4 Streak: Pale green Density: 4.0 Lustre: Earthy Habit: Very fine grained coating on other rocks, almost looks like paint.Colours: Copper green

Crystal System: MonoclinicCleavage: PerfectFracture: SubconchoidalMagnetism: NoneReaction with HCl: Strong

Identification in hand sample:Colour is primary indicator, as well as habit.

Associations:Common in near-surface oxidized portions of copper bearing hydrothermal sulfide mineral deposits.

Industrial / ecomonic uses:Used as a minor ore of copper and also has ornamental uses due to vivid green colour.

Carbonates

Siderite ---- FeCO3Hardness: 3.5 – 4 Streak: White Density: 4.0 Lustre: Vitreous Habit: Aggregate of crystals or grainsColours: Tan brown (typical)

Crystal System: HexagonalCleavage: Perfect rhombohedralFracture: UnevenMagnetism: NoneReaction with HCl: Weak

Identification in hand sample:Identified by colour and hardness.

Associations:Produced by hydrothermal alteration of limestone. May also occur as concretionary or oolitic forms in clay ironstones.

Industrial / ecomonic uses:Sometimes used as an iron ore. Also used in pigments where a red or brown colour is desirable.

Carbonates

Fluorite --- CaF2Hardness: 4 Streak: White Density: 3.1 - 3.3 Lustre: Vitreous Habit: Crystals, usually cubicColours: Commonly colourless, blue, purple or green, but any is possible.

Crystal System: IsometricCleavage: Perfect octahedralFracture: ConchoidalMagnetism: NoneReaction with HCl: Unknown

Identification in hand sample:Cubic crystals, hardness and colour indicative.

Associations:Common in hydrothermal mineral deposits associated with sulfides, carbonates and barite.

Industrial / ecomonic uses:Main source of fluorine (which is added to drinking water, toothpaste, used as a flux in industrial uses and as part of CFCs)

Halides

Halite (Salt) --- NaCl Hardness: 2 Streak: White Density: 2.1 - 2.2 Lustre: Waxy Habit: Crystalline (cubic)Colours: Colourless or white if pure, any colour if not

Crystal System: IsometricCleavage: CubicFracture: ConchoidalMagnetism: NoneReaction with HCl: None

Identification in hand sample:Has a salty taste. Cubic cleavage and hardness are indicative for the less brave geologists.

Associations:Abundant in marine evaporite deposits and may form beds hundreds to over a thousand meters thick. Associated minerals include calcite, dolomite, gypsum, anhydrite and sylvite.

Halides

Limonite-- FeO(OH)Hardness: 5 - 5.5 Streak: Yellow-brown Density: 2.7 - 4.3 Lustre: Earthy Habit: Fine grained aggregate, powdery coating.Colours: Orange, yellow-brown

Crystal System: UnknownCleavage: NoneFracture: UnevenMagnetism: NoneReaction with HCl: Very weak

Identification in hand sample:Colour is best indicator, followed by habit.

Associations:Common weathering product of iron-rich rocks.

Comments:The fine brownish coloured mineral is usually weathered goethite.

Hydroxide

Chromite (FeCr2O4)Hardness: 5.5 Streak: Brown Density: 4.5 - 4.8 Lustre: Metallic to pitchy Habit: Fine grained aggregate.Colours: Black

Crystal System: IsometricCleavage: NoneFracture: UnevenMagnetism: WeakReaction with HCl: Unknown

Identification in hand sample:Resembles magnetite and ilmenite, but not very magnetic and has a more resinous lustre.

Associations:Found in mafic and ultramafic igneous rocks such as gabbro, peridotite, dunite and pyroxenite as an accessory mineral.

Industrial / ecomonic uses:Only ore mineral for chromium.

Oxides

Corundum (Al2O3) Hardness: 9 Streak: White Density: 4.0 - 4.1 Lustre: Vitreous to adamantine Habit: Well-formed crystalsColours: Any. White, gray or gray-blue, or red (ruby), blue (sapphire), yellow, green.

Crystal System: HexagonalCleavage: NoneFracture: ConchoidalMagnetism: NoneReaction with HCl: None

Identification in hand sample:Hardness is best indicator, crystal habit is good too.

Associations:Gem quality corundum comes from metamorphed limestone or dolostone (needs high Al concentrations, here presumably from detrital deposits)

Industrial / ecomonic uses:Used as a gemstone. High-quality ruby can be more valuable than diamond. Corundum is also used as an abrasive in sandpaper, polishing compounds, etc.

Oxides

Hematite (massive) -- (Fe2O3) Hardness: 5 – 6 Streak: Deep red Density: 5.3 Lustre: Earthy Habit: Very fine grained aggregate of red crystals.Colours: Deep red

Crystal System: HexagonalCleavage: NoneFracture: SubconchoidalMagnetism: WeakReaction with HCl: Unknown

Identification in hand sample:Deep red streak and earthy lustre are indicative. SG may also be indicative.

Associations:Produced by weathering or hydrothermal alteration of iron-bearing minerals. May be found in some syenite, trachyte, granite and rhyolite.

Industrial / economic uses:Important ore or iron, sometimes used as a gemstone.

Comments:May become magnetic when heated.

Oxides

Hematite (specular) (Fe2O3) Hardness: 5 – 6 Streak: Deep red Density: 5.3 Lustre: Metallic Habit: Micaceous/tabular habit.Colours: Steel gray

Crystal System: HexagonalCleavage: NoneFracture: SubconchoidalMagnetism: NoneReaction with HCl: Unknown

Identification in hand sample:Shining gray metallic lustre and deep-red streak are indicative.

Associations:Produced by weathering and hydrothermal alteration of iron-bearing minerals.

Industrial / ecomonic uses:Important ore of iron.

Oxides

Magnetite (Fe3O4) Hardness: 5.5 - 6.5 Streak: Black Density: 5.2 Lustre: Dull metallic to splendent Habit: Granular habit of fine grains. Some octahedral crystals may form.Colours: Black

Crystal System: IsometricCleavage: NoneFracture: SubconchoidalMagnetism: StrongReaction with HCl: Unknown

Identification in hand sample:Highly magnetic. Habit and colour are also indicators.

Associations:Very common accessory mineral found in a wide variety of igneous and metamorphic rocks, usually as small grains.

Industrial / ecomonic uses:Mined for iron. Crushed magnetite also been used as aggregate to make high-density concrete for specialized applications, such as nuclear reactors.

Oxides

Pyrolusite (MnO2) Hardness: 2 - 6.5 Streak: Black Density: 5.1 Lustre: Earthy Habit: Massive, compact, columnar or fibrous. Prismatic crystals are rare. Sometimes forms as dendritic coatings on other rocks.Colours: Black

Crystal System: TetragonalCleavage: PerfectFracture: UnevenMagnetism: NoneReaction with HCl: Very weak

Identification in hand sample:Will leave sooty marks if touched.

Associations:Found in bog and marine deposits

Industrial / ecomonic uses:Manganese is used to colour bricks.

Oxides

Apatite Ca5(PO4)3( OH,F,Cl) Hardness: 5 Streak: White Density: 3.1 - 3.2 Lustre: Vitreous, glassy Habit: MassiveColours: Grayish blue-green, or any.

Crystal System: HexagonalCleavage: PoorFracture: ConchoidalMagnetism: NoneReaction with HCl: Weak

Identification in hand sample:Colour, crystal habit and hardness are good indicators.

Associations:Common accessory mineral in all environments.

Industrial / ecomonic uses:Source of phosphate used in fertilizers and other industrial applications. Fluorine is also extractable from apatite.

Comments:Same stuff as in bones and teeth.

Phosphates

Alabaster (Gypsum) CaSO4 - 2H2OHardness: 2 Streak: White Density: 2.3 Lustre: VitreousHabit: Granular / massive form of gypsumColours: Colourless or white (typical)

Crystal System: MonoclinicCleavage: PerfectFracture: SplinteryMagnetism: NoneReaction with HCl: Weak

Identification in hand sample:Identified by hardness and good cleavage.

Associations:Common in marine evaporite deposits.

Industrial / ecomonic uses:Modern use is in gypsum wallboard used in construction. Used as an ornamental stone and for sculpture due to its softness.

Sulfates

Barite (BaSO4) Hardness: 3 - 3.5 Streak: White Density: 4.5 Lustre: Vitreous Habit: Fine grained aggregatesColours: Colourless, white, gray, yellowish, brown,

reddish, bluish or greenishCrystal System: OrthorhombicCleavage: PerfectFracture: UnevenMagnetism: NoneReaction with HCl: None

Identification in hand sample:High specific gravity is best indicator, colour and fracture are also helpful.

Associations:Common in hydrothermal veins, associated with galena, sphalerite, pyrite, quartz, fluorite and carbonates.

Industrial / ecomonic uses:Primary ore for barium, also used as an additive to drilling mud (because of high SG). Has over 2000 uses in industry.

Sulfates

Selenite (Gypsum) CaSO4 - 2H2OHardness: 2 Streak: White Density: 2.3 Lustre: Vitreous Habit: Large crystalline habitColours: Colourless, clear

Crystal System: MonoclinicCleavage: PerfectFracture: SplinteryMagnetism: NoneReaction with HCl: Weak

Identification in hand sample:Single large crystals of gypsum, typified by hardness and transparency.

Associations:Found in marine evaporites.

Industrial / ecomonic uses:Used in gypsum wallboard.

Sulfates

Chalcocite (Cu2S) Hardness: 2.5 – 3 Streak: Blackish lead-gray Density: 5.5 - 5.8 Lustre: Dull metallicHabit: Chunky fracture, massive habit.Colours: Blackish lead-gray

Crystal System: MonoclinicCleavage: IndistinctFracture: ConchoidalMagnetism: NoneReaction with HCl: None

Identification in hand sample:Black colour with sooty appearance on weathered surfaces and sectile character are distinctive. Bronze-yellow on fresh surfaces.

Associations:Found in the supergene-enriched zone of copper-bearing hydrothermal sulfide deposits.

Industrial / ecomonic uses:Mined as a source of copper.

Sulfides

Chalcopyrite (CuFeS2)Hardness: 3.5 – 4 Streak: Greenish black Density: 4.3 - 4.4 Lustre: Metallic Habit: Fine grained to massive aggregates.Colours: Brass yellow, may be tarnished and iridescent.

Crystal System: TetragonalCleavage: PoorFracture: ConchoidalMagnetism: NoneReaction with HCl: Very weak

Identification in hand sample:Distinctive brassy-green colour. Has a richer yellow colour than pyrite and a lower hardness.

Associations:Most common copper-bearing mineral, found in many hydrothermal sulfide deposits. Often associated with galena, sphalerite, pyrite and other sulfides.

Industrial / ecomonic uses:Mined for its copper which has innumerable industrial uses.

Sulfides

Galena (PbS)Hardness: 2.5 Streak: Lead gray Density: 7.6 Lustre: MetallicHabit: Excellent cubic cleavage, crystals usually very evidentColours: Lead gray

Crystal System: IsometricCleavage: Perfect cubicFracture: SubconchoidalMagnetism: NoneReaction with HCl: Weak

Identification in hand sample:Gives off a rotten-egg smell in HCl, very high SG, very metallic lustre.

Associations:Very common in hydrothermal sulfide deposits. Associated with sphalerite, pyrite, chalcopyrite, quartz, calcite, fluorite, and/or barite.

Industrial / ecomonic uses:Main ore from which lead is extracted, also a source of silver.

Sulfides

Pyrite (crystalline) FeS2 Hardness: 6 - 6.5Density: 5.0 Lustre: Metallic Streak: Greenish/brownish black Habit: Perfect cubic crystalline habit. Colours: Bronze-yellow

Crystal System: IsometricCleavage: GoodFracture: ConchoidalMagnetism: UnknownReaction with HCl: None

Identification in hand sample:Colour, hardness, streak and habit are best indicators. Gives off sparks when struck with a hard metal object.

Associations:Most common sulfide mineral, almost always present in hydrothermal deposits.

Industrial / ecomonic uses:May be used as source of iron or sulfur, but not normally of economic value.

Sulfides

Stibnite (Sb2S3) Hardness: 2 Streak: Lead gray Density: 4.6 - 4.7 Lustre: MetallicHabit: Range from fine to medium grains to prismatic crystals (with longitudinal striations). Complex terminations, radiating acicular groups.Colours: Lead gray, black, iridescent tarnish

Crystal System: OrthorhombicCleavage: PerfectFracture: SubconchoidalMagnetism: NoneReaction with HCl: Weak

Identification in hand sample:Colour and small subhedral crystals are indicators. Also rather soft.

Associations:Forms in low-temperature hydrothermal veins, or is deposited from hot mineral springs.

Industrial / ecomonic uses:Important source of antimony (Sb)

Sulfides

Copper (Cu) Hardness: 2.5 - 3 Streak: Same

Density: 8.9 Lustre: Metallic Habit: Massive, platey or dendritic habit.Colours: Light rose on fresh surface, copper-red on tarnished surface

Crystal System: IsometricCleavage: NoneFracture: HacklyMagnetism: NoneReaction with HCl: Weak

Identification in hand sample:Colour and metallic characteristics are diagnostic.

Associations:Found associated with mafic volcanic rocks, formed by reaction between Cu-bearing solutions and Fe-bearing minerals. Associated minerals are cuprite, chalcocite, bornite, epidote, calcite, chlorite and zeolites.

Industrial / ecomonic uses:Used as electrical wire due to electrical conductivity and relatively low price.

Comments:Obviously a source of copper, however most copper in modern times is mined from sulfide minerals.

Native Elements

Graphite (C)Hardness: 1 – 2 Streak: Black Density: 2.1 - 2.3 Lustre: Dull metallic, greasy feel Habit: Fine grained aggregateColours: Silver-black

Crystal System: HexagonalCleavage: Perfect basalFracture: UnevenMagnetism: NoneReaction with HCl: None

Identification in hand sample:Softness and lustre are best indicators.

Associations:Common in pelitic metamorphic rocks such as phyllite, slate and schist. Produced as a result of decomposition of organic material.

Industrial / ecomonic uses:Used in pencil leads and as a dry lubricant.

Comments:Due to its softness, graphite is usually quite messy!

Native Elements

Cupit, Kerry. Mineral 1.0. 10June2011. Online. http://www.spaceman.ca/mineral/index.php

Reference