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Mineral Identification Lab Andrea Hoefner

Biotite Mica •

Chemical Formula: K(Mg,Fe)3(AlSi3O10)(F,OH)2

Lustre: Vitreous to pearly

Cleavage: Perfect on the {001}

Colour: Dark brown, greenish-brown, blackish-brown, yellow, white

Streak colour: White

Hardness: 2.5–3.0

Uses: Biotite is used extensively to constrain ages of rocks, by either potassium-argon dating or argon-argon dating.

Sources: “Virtural Mineral Lab

Calcite •

Chemical Formula: CaCO3

Lustre: Vitreous to pearly on cleavage surfaces

Cleavage: Perfect on [1011] three directions with angle of 74°

Colour: Colorless or white, also gray, yellow, green

Streak colour: White

Hardness: 3

Uses: High-grade optical calcite was used in World War II for gun sights, specifically in bomb sights and anti-aircraft weaponry, and concrete repair.

Feldspar •

Chemical Formula: Al(Al,Si)3O8.

Lustre: Vitreous

Cleavage: Two or three

Colour: Pink, white, gray, brown

Streak colour: White

Hardness: 6.0-6.5

Uses: A common raw material used in glassmaking, ceramics, and to some extent as a filler and extender in paint, plastics, and rubber.

Fluorite •

Chemical Formula: CaF2

Lustre: Non-metallic

Cleavage: Octahedral

Colour: Variations of purple

Streak Colour: Colourless

Hardness: 4 Softer than glass, harder than finger nail

Special Properties: Fluorescence under UV light

Optics, high-end telescopes and lenses: source fluoride in toothpaste

Galena • Chemical Formula: PbS • Lustre: Metallic • Cleavage: Cubic perfect on [001], parting on [111] • Colour: Lead gray and silvery • Streak Colour: Lead gray • Hardness: 2.5 • Uses: Galena is the primary ore of lead which is mainly used in making lead-acid batteries

Graphite •

Chemical Formula:




Streak Colour:



Gypsum • Chemical Formula: CaSO4·2H2O • Lustre: Vitreous, silky, pearly • Cleavage: Perfect on {010}, distinct on {100} • Colour: Colorless to white; may be yellow, tan, blue, pink, brown, reddish brown or gray due to impurities • Streak Colour: White • Hardness: 2 • Uses: Fertilizer, walls, floors, A wood substitute, in foot creams, and sheetrock or plasterboard.

Halite •

Chemical Formula: NaCl

Lustre: Vitreous

Cleavage: Perfect {001}, three directions cubic

Colour: Colorless or white; also blue, purple, red, pink, yellow, orange, or gray

Streak Colour: White

Hardness: 2-2.5

Uses: Halite is often used both residentially and municipally for managing ice, in cooking as a flavouring,

spread as salt.

Hematite •

Chemical Formula: Fe2O3, α-Fe2O3

Lustre: Metallic

Cleavage: None

Colour: Metallic gray, dull to bright red

Streak Colour: Bright red to dark red

Hardness: 5.5-6.5

Uses: Jewelry

Magnetite •

Chemical Formula: Fe2+Fe3+2O4

Lustre: Metallic

Cleavage: Indistinct

Colour: Black, gray with brownish tint in reflected sun

Streak Colour: Black

Hardness: 5.5–6.5

Uses: Magnetic iron oxides are often used in magnetic storage, for example in the magnetic layer of

hard disks, floppy disks and cassette tapes.

Muscovite Mica •

Chemical Formula: KAl2(AlSi3O10)(F,OH)2

Lustre: Vitreous, silky, pearly

Cleavage: Perfect on the 001

Colour: White, grey, silvery

Streak Colour: White

Hardness: 2–2.5

Uses: found in granites, pegmatites, gneisses, and schists, and as a contact metamorphic rock or as a

secondary mineral resulting from the alteration of topaz, feldspar, kyanite, etc.

Pyrite •

Chemical Formula: FeS2

Lustre: Metallic

Cleavage: Indistinct on {001}

Colour: Pale brass-yellow reflective; tarnishes darker

Streak Colour: Greenish-black to brownish-black

Hardness: 6-6.5

Uses: Commercial use for the production of sulfur dioxide, for use in such applications as the paper industry,

and in the manufacture of sulfuric acid.

Quartz •

Chemical Formula: SiO2

Lustre: Non-metallic, vitreous

Cleavage: Fracture

Colour: Colourless

Streak Colour: Colourless

Hardness: 7

Uses: Quartz is used in the making of sandpaper, optics, glass, liquid filters, circuit boards, computer

components, cement, mortar, meditation and jewelry

Sulfur •

Chemical Formula: S8

Lustre: Non-metallic

Cleavage: None

Colour: Yellow

Streak Colour: Yellow to white

Hardness: 1.5-2.5

Uses: Uses Elemental sulfur is used in black gunpowder, matches, and fireworks; in the vulcanization of rubber; as a fungicide, insecticide, and fumigant.

Talc •

Chemical Formula:

Lustre: Non-metallic, pearly

Cleavage: 1

Colour: White or greenish

Streak Colour: White to pearl green

Hardness: 1

Uses: paper making, plastic, paint and coatings, rubber, food, electric cable, pharmaceuticals, cosmetics, ceramics, etc.

Mineral identification lab andrea