Mineral Identification Tables PDF

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6/8/2020

Mineral Identification Tables

Mineral Identification Tables Table 1 MINERALS WITH METALLIC TO SUBMETALLIC LUSTER Name

H

Color

Streak

Prominent Cleavage

Molybdenite 1 - Lead-gray 1.5

greenish to YES - 1 dir. bluish gray (platy)

Graphite

gray to black

1 steel-gray to black

Composition

Other Properties

MoS2

Greasy feel; flexible plates

YES - 1 dir. (platy)

C

Greasy feel; flexible plates

Covellite

1.5 indigo-blue -2

gray to black

YES - 1 dir. (platy)

CuS

Iridescent yellow and red

Galena

2.5 Gray

gray

YES - 3 dir. at 90o

PbS

High specific gravity

Chalcocite

2.5 black to lead gray -3

black to lead gray

NO

Cu2S

Brittle, high specific gravity

grayish black

NO

Cu5FeS4

Also known as peacock ore

Chalcopyrite 3.5 brassy yellow, - 4 usually tarnished

greenish black

NO

CuFeS2

Softer than pyrite; most common copper mineral

Limonite (Goethite)

4 - Yellow-brown, 5.5 orange-brown, dark brown

yellowish brown to reddish

NO

Goethite: HFeO2

Mixture of rust-like iron oxides. Mostly mineral "goethite." Earthy to metallic luster. Stalactitic, botryoidal forms common.

Hematite

5.5 Steel-gray to reddish reddish - brown brown 6.5

NO

Fe2O3

Most common iron mineral; specular hematite variety is composed of fine silvery flakes

Magnetite

5.5 Black 6.5

black

NO (but sometimes shows parting)

Fe3O4

Strongly magnetic; lodestone variety shows polarity; often in octahedral (8-sided) crystals

Pyrite

6 - Pale brassy yellow 6.5

greenish to NO brownish black

FeS2

Known as "Fool's Gold." Brittle, common in crystals, but also granular and massive (no obvious form).

Bornite

3 bronze, but with copper-red to purplish iridescence

TABLE 2 MINERALS WITH NON-METALLIC LUSTER Name Talc

H 1

Color green, white, gray

Streak

Luster

Prominent Cleavage

white

pearly or greasy

YES - 1 dir. (Platy)

Composition

Other Properties

Mg3Si4010(OH)2 Called "soapstone." Flexible plates, very soft

Sulfur

1 - bright yellow 2.5

yellow

pearly

none

Realgar

1.5 - red to orange 2

orangered

resinous

YES - 1 dir., GOOD

colorless; white, gray, yellowish

white

vitreous

Only obvious in the selenite variety - 3 dir. (rhombic)

CaSO4.2H2O

Sylvite

2 - Colorless, white, 2.5 often reddish

white

vitreous

YES - 3 dir. at 90o

KCl

Bitter taste

Halite

2.5 Colorless, blue, yellow-blue

white

vitreous

YES - 3 dir. at 90o

NaCl

Salty taste, dissolves easily in water

Gypsum

2

Biotite Mica 2.5 Black, dark green, gray to or brown white

vitreous or YES - 1 dir. pearly (sheets)

Muscovite

vitreous

2.5 Colorless, gray, or

white

https://www.oakton.edu/user/4/billtong/eas100lab/mintable.htm

YES - 1 dir.

S AsS

K(Mg,Fe)3 (AlSi 3O10) (OH)2

low melting temperature Sectile; yellow powder common on surface 3 common varieties: -selenite: clear, transparent -satin spar: fibrous, silky -alabaster: granular, sugary

Flexible and elastic sheets

Kal2(AlSi 3O10) Flexible and elastic sheets 1/3

6/8/2020

Mineral Identification Tables

Mica Bauxite

Calcite

green 2 - 7 white to brown

3

(sheets) white

earthy-dull NO

(OH)2 Mixture of AlO(OH), Al(OH 3, and HAlO2

Mixture of 3 clay minerals: Boehmite, Gibbsite, and Diaspore. Earthy odor when breathed on.

colorless or white; white impurities may discolor it yellow or brown

vitreous

YES - 3 dir., not at 90o (rhombic)

CaCO3

Effervesces vigorously with cold dilute hydrochloric acid. Transparent calcite shows double refraction.

YES - 2 dir. (seen in crystalline forms)

BaSO4

High specific gravity (4.5). Ground-up barite is used as an weighting additive for drilling muds.

Barite

3 - Colorless, white; 3.5 impurities may discolor it brown, red, or yellow

white

vitreous

Dolomite

3 - White, gray, 3.5 brown, pink

white

vitreous to YES, but not pearly always obvious (rhombic).

Malachite

3.5 - bright green 4

pale green

velvety, silky or dull

Sphalerite

3.5 - dark brown or 4 black to yellow

light resinous to YES - 6 dir. yellow to sub(all 6 brown metallic directions not always obvious)

ZnS

Reacts with hydrochloric acid only when powdered to produce hydrogen sulfide gas.

Cubic crystals common, 8-sided diamond-shaped crystals sometimes seen; often fluorescent

Not obvious in rock masses

CaMg(CO3 ) 2

Cu2(CO3)(OH)2 Effervesces in hydrochloric acid. Frequently in banded, botryoidal masses. Flame test produces green color.

Fluorite

4

colorless, white, yellow, purple, blue, green

white

vitreous

YES - 4 dir. (all 4 directions not always obvious)

CaF2

Apatite

5

shades of yellow, white green, blue, brown

vitreous

Not obvious indistinct

Ca5(PO4) 3 (F,Cl,OH)

Limonite (Goethite) Hematite

yellowish earthy, dull NO 4 - Yellow-brown, 5.5 orange-brown, dark brown to reddish brown 5.5.- Red and reddish 6.5 brown

reddish brown

dull to sub- NO metallic

Effervesces slowly with dilute cold hydrochloric acid, but only when powdered

Commonly seen as 6-sided prismatic crystals

Goethite: HfeO2 Ordinary "rust" - a mixture of iron oxides, composed mostly of goethite. Fe2O3

Commonly appears in these forms: oolitic, botryoidal, or massive (no obvious form)

Augite (pyroxene)

6

dark green to black gray

vitreous

YES - 2 dir. at complex silicate Most common pyroxene; often appears as short, stubby, nearly 90o prismatic crystals in rock.

Hornblende (amphibole)

6

black, dark green, or brown

grayishwhite

vitreous

YES - 2 complex silicate directions, ith angles at 56o and 24o

Olivine

6

olive green or brownish

white or gray

vitreous to Not obvious adamantine indistinct

Plagioclase feldspar (including Albite, Labradorite, etc.)

6

white to dark gray

colorless vitreous or white

Potassium feldspar

6

YES - 2 dir. at nearly 90o

(Mg,Fe) 2 SiO4 Often found as "sugary" granular masses of dunite (olivine rock); gem variety called peridot NaAlSi3O8 to CaAlSi2O8

white, tan to colorless vitreous or YES - 2 dir. at orange, red, green, or white pearly nearly 90o also colorless

https://www.oakton.edu/user/4/billtong/eas100lab/mintable.htm

Most common amphibole; found in many igneous rocks. Characterized by dark, elongated crystals

KAlSi3O8

Sodium-rich varieties are white or light gray; calcium-rich varieties are medium to dark gray. Labradorite variety shows blue play of colors. Most commonly found in granites and pegmatites.

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Mineral Identification Tables

(Orthoclase, Microcline) Quartz (crystalline varieties)

7

colorless, white, colorless vitreous gray, purple, pink, black, yellow, green

NO - shows conchoidal fracture

SiO2

Varieties named by color: Rock crystal (colorless), Milky (white), Smoky (gray), Amethyst (purple), Rose (pink), Citrine (yellow); 6-sided crystals common

Silica (Chalcedony varieties)

7

all colors observed colorless waxy or dull usually

NO conchoidal fracture predominant

SiO2

Collectively called "chalcedony" Agate (banded), Jasper (red or brown), Chert or Flint (white, gray or black)

Garnet 7 - commonly red and colorless vitreous or NO - but silicates of Al, 7.5 brown; also yellow, to pale resinous sometimes Ca, Mg, Ge, Mn, group pink, green, black brown shows parting Cr (Almandine, etc.) Tourmaline

Corundum

7 - black; also green, 7.5 pink, brown 9

colorless vitreous

Not obvious - complex silicate Common in 3-sided crystals, indistinct of B, Al, Fe, Mg often prismatic with striations or columnar structure

gray, brown, blue, colorless dull, NO - but red, colorless vitreous, common adamantine shows parting

https://www.oakton.edu/user/4/billtong/eas100lab/mintable.htm

Commonly found in metamorphic rocks (transformed from plagioclase); 12-sided (dodecahedral) crystals are common

Al2O3

Often in barrel-shaped crystals. Clear gem varieties include: -sapphire(blue) -ruby (red) -emerald (green) Granular form is called emery

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