Page 111 - Laboratory Manual in Physical Geology

MINERAL DATABASE (Alphabetical Listing)

Luster and
Mineral Crystal Hardness Streak Distinctive Some Uses
System Properties
LIMONITE Metallic (M) 1–5.5 Yellow- Color yellow-brown to dark brown; Yellow ochre pigment in paint
Fe 2 O 3 · nH 2 O or brown Tarnishes yellow to brown; and cosmetics. Ore of iron for
hydrated iron oxide Nonmetallic Amorphous masses; Luster dull or iron and steel used in machines,
and/or (NM) earthy; Hard or soft; SG = 3.3–4.3 buildings, bridges, nails, tools,
FeO(OH) · nH 2 O file cabinets; Added to pills and
hydrated iron oxide foods to aid hemoglobin
hydroxide Amorphous production in red blood cells
MAGNETITE Metallic (M) 6–6.5 Dark gray Color silvery gray to black; Opaque; Ore of iron for iron and steel
or Forms octahedrons; Tarnishes gray; used in machines, buildings,
Fe 3 O 4
iron oxide Nonmetallic No cleavage; Attracted to a magnet bridges, nails, tools, file
(NM) and can be magnetized; SG = 5.0–5.2 cabinets; Added to pills and
foods to aid hemoglobin
Isometric production in red blood cells
MALACHITE Nonmetallic 3.5–4 Green Color green, pale green, or gray- Ore of copper, used to make
(NM) green; Usually in crusts, laminated pipes, electrical wire, coins,
Cu 2 CO 3 (OH) 2
copper carbonate masses, or microcrystals; Effervesces ammunition, bronze, brass;
hydroxide in dilute HCl; SG = 3.6–4.0 added to vitamin pills for healthy
Monoclinic hair and skin; Gemstone
MICA: See BIOTITE and MUSCOVITE
MUSCOVITE MICA Nonmetallic 2–2.5 White Colorless, yellow, brown, or red- Computer chip substrates,
potassium hydrous (NM) brown; Forms short opaque prisms; electrical insulation, roof
aluminum silicate Cleavage excellent in 1 direction, can shingles, Cosmetics with a
be split into thin flexible transparent satiny sheen
KAl 2 (Al,Si 3 O 10 )(OH,F) 2
Monoclinic sheets; SG = 2.7–3.0
NATIVE COPPER: See COPPER
NATIVE GOLD: See GOLD

NATIVE SILVER: See SILVER
NATIVE SULFUR: See SULFUR
NATROLITE Nonmetallic 5–5.5 White Colorless, white, gray, or pale Used in water softeners
(ZEOLITE) (NM) green, yellow, or red; Forms
Na 2 (Al 2 Si 3 O 10 ) · 2H 2 O masses of radiating needles;
hydrous sodium Silky luster; SG = 2.2–2.4
aluminum silicate Orthorhombic
OLIVINE Nonmetallic 7 White* Color pale or dark olive-green to Green gemstone (peridot); Ore
(NM) yellow, or brown; Forms short crystals of magnesium used to make
(Fe,Mg) 2 SiO 4
ferromagnesian that may resemble sand grains; paper; lightweight frames for
silicate Conchoidal fracture; Cleavage absent; jet engines, cell phones,
Brittle; SG = 3.3–3.4 laptops; pills for good brain,
Orthorhombic muscle, and skeletal health
OPAL Nonmetallic 5–5.5 White Colorless to white, orange, yellow, Gemstone
SiO 2 · nH 2 O (NM) brown, blue, gray, green, or red; may
hydrated silicon have play of colors (opalescence);
dioxide Amorphous; Cleavage absent;
Amorphous Conchoidal fracture; SG = 1.9–2.3
PLAGIOCLASE Nonmetallic 6 White Colorless, white, gray, or black; May Used to make ceramics, glass,
FELDSPAR (NM) have iridescent play of color from enamel, soap, false teeth,
NaAlSi 3 O 8 to within; Translucent; Forms striated scouring powders
tabular crystals or blades; Cleavage
CaAl 2 Si 2 O 8
calcium-sodium good in two directions at nearly 90°;
aluminum silicate Triclinic SG = 2.6–2.8
POTASSIUM Nonmetallic 6 White Color orange, brown, white, green, Used to make ceramics, glass,
FELDSPAR (NM) or pink; Forms translucent prisms enamel, soap, false teeth,
with subparallel exsolution lamellae; scouring powders
KAlSi 3 O 8
potassium aluminum Cleavage excellent in two directions
silicate Monoclinic at nearly 90°; SG = 2.5–2.6
PYRITE Metallic 6–6.5 Dark gray Color silvery gold; Tarnishes brown; Ore of sulfur for matches,
(“fool’s gold”) (M) H 6–6.5; Cleavage absent to poor; gunpowder, fertilizer, rubber
Brittle; Forms opaque masses, cubes hardening (car tires), fungicide,
FeS 2
iron sulfide (often striated), or pyritohedrons; insecticide, paper pulp
Isometric
SG = 4.9–5.2 processing
PYRRHOTITE Metallic 3.5–4.5 Dark gray Color brassy to brown-bronze; Ore of iron and sulfur; Impure
(M) to black Tarnishes dull brown, sometimes with forms contain nickel and are
FeS faint iridescent colors; Fracture used as nickel ore; the nickel is
iron sulfide uneven to conchoidal; No cleavage; used to make stainless steel
Monoclinic attracted to a magnet; SG = 4.6
*Streak cannot be determined with a streak plate for minerals harder than 6.5. They scratch the streak plate.
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