Tables for identification of minerals
Source; Kansas Geological Survey
I. Metallic or submetallic luster
A. Will mark paper (hardness less than 2 1/2)
Streak
Color
Black
Black
Hardness
Remarks
1-2
May be in radiating fibrous masses
Name,
composition
Pyrolusite, MnO2
Gray-black
Lead-gray
to blueblack
2 1/2
In cubic crystals with perfect cleavage. May be
massive granular. Small globules of metallic lead
Galena, PbS
collect on surface of fragment held in candle
flame.
Yellow-brown (to
dark-brown or
black)
Yellowbrown
1+
Earthy. Usually much harder. Apparently
noncrystalline
Limonite,
FeO(OH)·nH2O +
Fe2O3•nH2O
B. Will not readily mark paper, but can be scratched by knife (hardness 2 1/2 to 5 1/2)
Streak
Color
Brassyellow
Hardness
Remarks
Name,
composition
3 1/2-4
Commonly massive. Associated with dolomite,
galena, and sphalerite in Tri-State area
Black or brownish
Black
black
5-6
Massive, may occur as coatings. Associated with Psilomelane, primarily
pyrolusite
MnO2
Light- to darkBrown to
brown (lighter than
black
specimen)
3 1/2-4
Perfect cleavage in six directions. Resinous luster. Sphalerite, ZnS
Black
Yellow-brown
Dark-brown
5-5 1/2
to black
Glassy luster. Seemingly noncrystalline
Chalcopyrite, CuFeS2
Limonite,
FeO(OH)•nH2O +
Fe2O3•nH2O
C. Cannot be scratched by knife
(hardness greater than 5 1/2)
Streak
Black
Dark-brown to
black
Yellow-brown
Color
Hardness
Remarks
Name,
composition
Pale brass6-6 1/2
yellow
Massive granular. Commonly in striated cubes or
Pyrite, FeS2
pyritohedrons
Very pale
yellow
6-6 1/2
Commonly in "cockscombs" or radiating fibrous
structures
Black
6
Strongly magnetic. Crystals are small octahedrons Magnetite, Fe3O4
Black
5 1/2-6
Commonly massive granular
5-6
Massive, may occur as coatings. Associated with Psilomelane, primarily
pyrolusite
MnO2
Black
Dark-brown
5-5 1/2
to black
Glassy luster. Seemingly noncrystalline
Marcasite, FeS2
Ilmenite, FeTiO3
Limonite,
FeO(OH)•nH20 +
Fe2O3•nH20
II. Nonmetallic luster
A. Colored streak
Streak
Color
Hardness
Remarks
Name,
composition
Red-brown
Dark reddishbrown to steelgray to black
5 1/2-6
1/2
Massive; radiating. Some varieties
softer. Coloring matter in some
sandstones (brownish-red)
Hematite, Fe2O3
Yellow-brown
Yellow-brown
to black
5-5 1/2
Earthy to hard, with glassy luster.
Seemingly noncrystalline
Limonite,
FeO(OH)•nH20 +
Fe2O3•nH20
Light-brown
Light to darkbrown
3 1/2-4
Perfect cleavage in six directions.
Resinous luster
Sphalerite, ZnS
Pale-yellow
Pale-yellow
1 1/2-2
1/2
Granular, earthy, crystallized. Burns
with blue flame, giving sulfur dioxide Sulfur, S
odor
Light-green
Bright-green
3 1/2-4
Radiating, fibrous. Occurs as small
specks in some dolomite beds
B. Colorless streak
1. Can be scratched by fingernail (hardness less than 2 1/2)
Malachite,
Cu2CO3(OH)2
Cleavage, fracture
Perfect cleavage in one
direction (the micas)
Color
Hardness
Remarks
Name,
composition
Golden yellowbrown;
1 -1 1/2
brownish-red
As small scales or "books." Expands
when heated
Vermiculite,
(Mg,Fe)3(Si,Al,Fe)4
O10(OH)2•4H2O
Greenish-white;
yellowish;
2-2 1/2
colorless
As small scales or "books"
Muscovite mica,
KAl2Si3O10(OH)2
Dark-brown,
green to black
2 1/2-3
As small scales or "books"
Biotite mica,
K(Mg,Fe)3AlSi3O10
(OH)2
Yellowishbrown
2 1/2-3
As small scales or "books" with
copperlike reflection from cleavage
faces
Phlogopite mica,
KMg3AlSi3010 (OH)2
Perfect cleavage in one
Colorless, white,
direction; good cleavage
2
gray pink
in two directions
1 1/2-2
1/2
In flat crystals, broad cleavage flakes
(selenite) or compact massive without
Gypsum, CaSO4•2H2O
cleavage, or fibrous with silky luster
(satin spar)
Granular, earthy, crystallized. Burns
with blue flame, giving sulfur-dioxide Sulfur, S
odor
Uneven fracture
Pale-yellow
Conchoidal fracture
Light yellowish2-2 1/2
brown
Resinous luster. Very lightweight.
Not a true mineral
Amber, oxygenated
hydrocarbon
One perfect cleavage,
rarely seen
White, reddish,
or yellowish
2
Long needlelike crystals; on mine
walls, Tri-State district
Goslarite, ZnSO4•7H2O
Indistinct
Greenish-white
to white
2
Very fine fibrous masses, associated
with marcasite and pyrite. Sweetish,
metallic, bitter taste
Melanterite,
FeSO4•7H2O
2. Cannot be scratched by fingernail but can be scratched by knife (hardness 2 1/2-5 1/2)
Cleavage, fracture
Color
Hardness
Remarks
Name, composition
Perfect cleavage in three Colorless, white,
2 1/2
directions at right angles red, blue
Common salt, soluble in water. Salty
taste. Granular cleavable masses or
Halite, NaCl
cubic crystals
Cleavage in three
Colorless, white,
directions at right angles
3-3 1/2
bluish-gray, red
(no cleavage if massive)
Crystals rare. Commonly in massive
fine aggregates (not showing
cleavage) associated with gypsum;
massive variety can be distinguished
only by chemical tests
Perfect cleavage in three
Colorless, white,
directions not at right
3
and various tints
angles (rhombohedral)
Effervesces in cold acid. Many crystal
forms. Chief mineral in limestone.
Calcite, CaCO3
Fibrous, banded, and granular
varieties do not show cleavage
Perfect cleavage in two
directions at right
angles; imperfect
cleavage in third
direction
White, blue,
yellow, pink
3-3 1/2
Three perfect cleavage
directions not at right
angles (rhombohedral)
Commonly in aggregates of tabular
crystals. Heavier than most
Barite, BaSO4
nonmetallic minerals (differentiated
from celestite). In sand-barite rosettes
White, blue, red 3-3 1/2
Similar to barite. Distinguished by
crimson flame test
Colorless or
white
3-3 1/2
Small splinter fusible in candle flame,
producing lead globules. Hard,
Cerussite, PbCO3
brilliant luster. Granular masses and
platy crystals, associated with galena
Yellow
3-3 1/2
Fine coating on sphalerite and other
minerals in Tri-State district.
Resinous to earthy luster
Greenockite, CdS
Colorless, white,
3 1/2-4
various tints
Effervesces in cold acid, falls to
powder in candle flame. May be in
radiating needlelike crystals
Aragonite, CaCO3
Colorless, white,
3
various tints
Effervesces in cold acid. Many crystal
forms. Chief mineral in limestone.
Calcite, CaCO3
Fibrous, banded, and granular
varieties do not show cleavage
Colorless, white,
3 1/2-4
pink
Commonly in curved rhombohedral
crystals with pearly luster. In granular
masses as dolomite limestones.
Dolomite, CaMg(CO3)2
Powdered mineral effervesces mildly
in cold acid
Cleavage not prominent
One cleavage direction,
indistinct
Anhydrite, CaSO4
Celestite, SrSO4
Light- to darkbrown
3 1/2-4
In cleavable masses or small curved
rhombohedral crystals. Also fine
granular (without cleavage). Becomes Siderite, FeCO3
magnetic after heating in candle
flame. Occurs in clay ironstones
Perfect cleavage in six
directions
Yellow, brown
3 1/2-4
Resinous luster. In small four-sided
crystals or in cleavable masses. May
be massive
Sphalerite, ZnS
Conchoidal fracture
Colorless, white,
yellow, red,
5-6
brown, green,
gray, blue
Seemingly noncrystalline. Hardness
less than fine-grained quartz
Opal, SiO2•nH20
Cleavage rarely seen
Brown, green,
4-5
blue, pink, white
In rounded globular forms or
honeycomb masses. Rare rhombshaped crystals. Effervesces in cold
acid
Smithsonite, ZnCO3
Cleavage in two
directions, rarely seen
White, palegreen, blue
Radiating crystal groups and globular Hemimorphite,
forms
Zn4Si2O7(OH)2•H2O
4 1/2-5
3. Cannot be scratched by knife but can be scratched by quartz (hardness 5 1/2 to 7)
Cleavage, fracture
Color
White, gray,
Two cleavage directions
bluish, pink,
at nearly 90° angles
green
Conchoidal fracture
Hardness
Remarks
Name, composition
In cleavable masses or irregular
grains in rocks. Common in stream
gravel
Feldspar, KAlSi3O8, or
NaAlSi3O8 to
CaAl2Si2O8
Colorless, white,
yellow, red,
5-6
brown, green,
gray, blue
Seemingly noncrystalline. Hardness
less than fine-grained quartz
Opal, SiO2•nH20
Gray, lightbrown, cream,
yellow, red,
green
Waxy to dull luster. May be banded
or lining cavities. Cryptocrystalline
quartz
Chalcedony, SiO2
6
7
Colorless, white,
amethyst,
7
variously tinted
Crystals are six-sided prisms capped
by pyramids. Often massive, coarsely Quartz, SiO2
crystalline. Glassy to greasy luster
4. Cannot be scratched by quartz (hardness greater than 7)
Cleavage, fracture
Color
Hardness
Conchoidal fracture
Colorless, white,
amethyst,
7
various tinted
Uneven to
subconchoidal fracture
Brown, red
6 1/2-7
1/2
Remarks
Name,
composition
Crystals are six-sided prisms capped
by pyramids. Often massive, coarsely Quartz, SiO2
crystalline. Glassy to greasy luster
Crystals have many faces of about
equal size. Glassy luster
Garnet, silicates of Al,
Ca, Mg, Fe, Mn, or Cr