Page 110 - Laboratory Manual in Physical Geology

MINERAL DATABASE (Alphabetical Listing)

Luster and Distinctive
Mineral Crystal Hardness Streak Properties Some Uses
System
GALENA Metallic 2.5 Gray to Color bright silvery gray; Tarnishes dull Ore of lead for television
PbS (M) dark gray gray; Forms cubes and octahedrons; glass, auto batteries,
lead sulfide Brittle; Cleavage good in three solder, ammunition; May
directions, so breaks into cubes; be an ore of bismuth (an
Isometric SG = 7.4–7.6 impurity) used as a lead
substitute in pipe solder
and fishing sinkers; May
be an ore of silver (an
impurity) used in jewelry,
electrical circuit boards
GARNET Nonmetallic 7 White* Color usually red, black, or brown, Used as an abrasive;
complex silicate (NM) sometimes yellow, green, pink; Red gemstone
Forms dodecahedrons; Cleavage
Isometric absent but may have parting; Brittle;
Translucent to opaque; SG = 3.5–4.3
GOETHITE Metallic 5–5.5 Yellow-brown Color dark brown to black; Ore of iron for iron and
FeO(OH) (M) Tarnishes yellow-brown; Forms steel used in machines,
iron oxide hydroxide layers of radiating microscopic buildings, bridges, nails,
crystals; SG = 3.3–4.3 tools, file cabinets; Added
to pills and foods to aid
hemoglobin production in
Orthorhombic
red blood cells
GOLD Metallic 2.5–3.0 Gold-yellow Color gold to yellow-gold; Does not Ductile and malleable
(NATIVE GOLD) (M) tarnish; Ductile, malleable and sectile; metal used for jewelry;
Au Hackly fracture; SG = 19.3; No cleavage; Electrical circuitry in
pure gold Forms odd-shaped masses, nuggets, computers, cell phones,
and dendritic forms car air bags; Heat shields
Isometric
for satellites
GRAPHITE Metallic 1 Dark gray Color dark silvery gray to black; Forms Used for pencils, anodes
C (M) flakes, short hexagonal prisms, and (negative ends) of most
carbon earthy masses; Greasy feel; Very batteries, synthetic motor
soft; Cleavage excellent in 1 oil, carbon steel, fishing
Hexagonal direction; SG = 2.0–2.3 rods, golf clubs
GYPSUM Nonmetallic 2 White Colorless, white, or gray; Forms Plaster-of-paris,
CaSO 4 · 2H 2 O (NM) tabular crystals, prisms, blades, wallboard, drywall, art
hydrated calcium or needles (satin spar variety); sculpture medium
sulfate Monoclinic Transparent to translucent; Very (alabaster)
soft; Cleavage good; SG = 2.3
HALITE Nonmetallic 2.5 White Colorless, white, yellow, blue, brown, Table salt, road salt;
NaCl (NM) or red; Transparent to translucent; Used in water softeners
sodium chloride Brittle; Forms cubes; Cleavage and as a preservative;
Isometric excellent in 3 directions, so breaks Sodium ore
into cubes; Salty taste; SG = 2.1–2.6
HEMATITE Metallic (M) 1–6 Red to Color silvery gray, reddish silver, black, Red ochre pigment in
or red-brown or brick red; Tarnishes red; Opaque; paint and cosmetics. Ore
Fe 2 O 3
iron oxide Nonmetallic Soft (earthy) and hard (metallic) varieties of iron for iron and steel
(NM) have same streak; Forms thin tabular used in machines,
crystals or massive; May be attracted buildings, bridges, nails,
Hexagonal to a magnet; SG = 4.9–5.3 tools, file cabinets; Added
to pills and foods to aid
hemoglobin production in
red blood cells
HORNBLENDE Nonmetallic 5.5–6.0 White to Color dark gray to black; Fibrous varieties used for
(amphibole) calcium (NM) pale gray Forms prisms with good cleavage fire-resistant clothing,
ferromagnesian at 56° and 124°; Brittle; Splintery or tiles, brake linings
aluminum silicate Monoclinic asbestos forms; SG = 3.0–3.3
JASPER Nonmetallic 7 White* Color red-brown, or yellow; Opaque; Used as an abrasive;
(NM) Waxy luster; Conchoidal fracture; Used to make glass,
SiO 2
cryptocrystalline No visible Cryptocrystalline; SG = 2.5–2.8 gemstones
quartz crystals
KAOLINITE Nonmetallic 1–2 White Color white to very light brown; Used for pottery, clays,
(NM) Commonly forms earthy, microcrystalline polishing compounds,
Al 4 (Si 4 O 10 )(OH) 8
aluminum silicate Triclinic masses; Cleavage excellent but absent in pencil leads, paper
hydroxide hand samples; SG = 2.6
K-SPAR: See POTASSIUM FELDSPAR
KYANITE Nonmetallic 4–7 White* Color blue, pale green, white, or gray; High temperature
Al 2 (SiO 4 )O (NM) Translucent to transparent; Forms ceramics, spark plugs
aluminum silicate Triclinic blades; SG = 3.6–3.7
oxide
*Streak cannot be determined with a streak plate for minerals harder than 6.5. They scratch the streak plate.
Mineral Properties, Identification, and Uses ■ 95