Tables for identification of Kansas minerals

I. Metallic or submetallic luster

A. Will mark paper (hardness less than 2 1/2)
Streak Color Hardness Remarks Name,
composition
Black Black 1-2 May be in radiating fibrous masses Pyrolusite, MnO2
Gray-black Lead-gray to blue-black 2 1/2 In cubic crystals with perfect cleavage. May be massive granular. Small globules of metallic lead collect on surface of fragment held in candle flame. Galena, PbS
Yellow-brown (to dark-brown or black) Yellow-brown 1+ Earthy. Usually much harder. Apparently noncrystalline Limonite, FeO(OH)·nH2O + Fe2O3nH2O
B. Will not readily mark paper, but can be scratched by knife (hardness 2 1/2 to 5 1/2)
Streak Color Hardness Remarks Name,
composition
Black Brass-yellow 3 1/2-4 Commonly massive. Associated with dolomite, galena, and sphalerite in Tri-State area Chalcopyrite, CuFeS2
Black or brownish black Black 5-6 Massive, may occur as coatings. Associated with pyrolusite Psilomelane, primarily MnO2
Light- to dark-brown (lighter than specimen) Brown to black 3 1/2-4 Perfect cleavage in six directions. Resinous luster. Sphalerite, ZnS
Yellow-brown Dark-brown to black 5-5 1/2 Glassy luster. Seemingly noncrystalline Limonite, FeO(OH)•nH2O + Fe2O3nH2O
C. Cannot be scratched by knife
(hardness greater than 5 1/2)
Streak Color Hardness Remarks Name,
composition
Black Pale brass-yellow 6-6 1/2 Massive granular. Commonly in striated cubes or pyritohedrons Pyrite, FeS2
Very pale yellow 6-6 1/2 Commonly in "cockscombs" or radiating fibrous structures Marcasite, FeS2
Black 6 Strongly magnetic. Crystals are small octahedrons Magnetite, Fe3O4
Dark-brown to black Black 5 1/2-6 Commonly massive granular Ilmenite, FeTiO3
Black 5-6 Massive, may occur as coatings. Associated with pyrolusite Psilomelane, primarily MnO2
Yellow-brown Dark-brown to black 5-5 1/2 Glassy luster. Seemingly noncrystalline Limonite, FeO(OH)•nH20 + Fe2O3nH20

II. Nonmetallic luster

A. Colored streak
Streak Color Hardness Remarks Name,
composition
Red-brown Dark reddish-brown to steel-gray 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 + Fe2O3nH20
Light-brown Light to dark-brown 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 odor Sulfur, S
Light-green Bright-green 3 1/2-4 Radiating, fibrous. Occurs as small specks in some dolomite beds Malachite, Cu2CO3(OH)2
B. Colorless streak
1. Can be scratched by fingernail (hardness less than 2 1/2)
Cleavage, fracture Color Hardness Remarks Name,
composition
Perfect cleavage in one direction (the micas) Golden yellow-brown; brownish-red 1 -1 1/2 As small scales or "books." Expands when heated Vermiculite, (Mg,Fe)3(Si,Al,Fe)4 O10(OH)2•4H2O
Greenish-white; yellowish; colorless 2-2 1/2 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
Yellowish-brown 2 1/2-3 As small scales or "books" with copperlike reflection from cleavage faces Phlogopite mica, KMg3AlSi3010 (OH)2
Perfect cleavage in one direction; good cleavage in two directions Colorless, white, gray pink 2 In flat crystals, broad cleavage flakes (selenite) or compact massive without cleavage, or fibrous with silky luster (satin spar) Gypsum, CaSO4•2H2O
Uneven fracture Pale-yellow 1 1/2-2 1/2 Granular, earthy, crystallized. Burns with blue flame, giving sulfur-dioxide odor Sulfur, S
Conchoidal fracture Light yellowish-brown 2-2 1/2 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 directions at right angles Colorless, white, red, blue 2 1/2 Common salt, soluble in water. Salty taste. Granular cleavable masses or cubic crystals Halite, NaCl
Cleavage in three directions at right angles (no cleavage if massive) Colorless, white, bluish-gray, red 3-3 1/2 Crystals rare. Commonly in massive fine aggregates (not showing cleavage) associated with gypsum; massive variety can be distinguished only by chemical tests Anhydrite, CaSO4
Perfect cleavage in three directions not at right angles (rhombohedral) Colorless, white, and various tints 3 Effervesces in cold acid. Many crystal forms. Chief mineral in limestone. Fibrous, banded, and granular varieties do not show cleavage Calcite, CaCO3
Perfect cleavage in two directions at right angles; imperfect cleavage in third direction White, blue, yellow, pink 3-3 1/2 Commonly in aggregates of tabular crystals. Heavier than most nonmetallic minerals (differentiated from celestite). In sand-barite rosettes Barite, BaSO4
White, blue, red 3-3 1/2 Similar to barite. Distinguished by crimson flame test Celestite, SrSO4
Cleavage not prominent Colorless or white 3-3 1/2 Small splinter fusible in candle flame, producing lead globules. Hard, brilliant luster. Granular masses and platy crystals, associated with galena Cerussite, PbCO3
Yellow 3-3 1/2 Fine coating on sphalerite and other minerals in Tri-State district. Resinous to earthy luster Greenockite, CdS
One cleavage direction, indistinct Colorless, white, various tints 3 1/2-4 Effervesces in cold acid, falls to powder in candle flame. May be in radiating needlelike crystals Aragonite, CaCO3
Three perfect cleavage directions not at right angles (rhombohedral) Colorless, white, various tints 3 Effervesces in cold acid. Many crystal forms. Chief mineral in limestone. Fibrous, banded, and granular varieties do not show cleavage Calcite, CaCO3
Colorless, white, pink 3 1/2-4 Commonly in curved rhombohedral crystals with pearly luster. In granular masses as dolomite limestones. Powdered mineral effervesces mildly in cold acid Dolomite, CaMg(CO3)2
Light- to dark-brown 3 1/2-4 In cleavable masses or small curved rhombohedral crystals. Also fine granular (without cleavage). Becomes magnetic after heating in candle flame. Occurs in clay ironstones Siderite, FeCO3
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, brown, green, gray, blue 5-6 Seemingly noncrystalline. Hardness less than fine-grained quartz Opal, SiO2nH20
Cleavage rarely seen Brown, green, blue, pink, white 4-5 In rounded globular forms or honeycomb masses. Rare rhomb-shaped crystals. Effervesces in cold acid Smithsonite, ZnCO3
Cleavage in two directions, rarely seen White, pale-green, blue 4 1/2-5 Radiating crystal groups and globular forms Hemimorphite, Zn4Si2O7(OH)2•H2O
3. Cannot be scratched by knife but can be scratched by quartz (hardness 5 1/2 to 7)
Cleavage, fracture Color Hardness Remarks Name, composition
Two cleavage directions at nearly 90° angles White, gray, bluish, pink, green 6 In cleavable masses or irregular grains in rocks. Common in stream gravel Feldspar, KAlSi3O8, or NaAlSi3O8 to CaAl2Si2O8
Conchoidal fracture Colorless, white, yellow, red, brown, green, gray, blue 5-6 Seemingly noncrystalline. Hardness less than fine-grained quartz Opal, SiO2nH20
Gray, light-brown, cream, yellow, red, green 7 Waxy to dull luster. May be banded or lining cavities. Cryptocrystalline quartz Chalcedony, SiO2
Colorless, white, amethyst, variously tinted 7 Crystals are six-sided prisms capped by pyramids. Often massive, coarsely crystalline. Glassy to greasy luster Quartz, SiO2
4. Cannot be scratched by quartz (hardness greater than 7)
Cleavage, fracture Color Hardness Remarks Name,
composition
Conchoidal fracture Colorless, white, amethyst, various tinted 7 Crystals are six-sided prisms capped by pyramids. Often massive, coarsely crystalline. Glassy to greasy luster Quartz, SiO2
Uneven to subconchoidal fracture Brown, red 6 1/2-7 1/2 Crystals have many faces of about equal size. Glassy luster Garnet, silicates of Al, Ca, Mg, Fe, Mn, or Cr


Source: Kansas Rocks and Minerals, L. L. Tolsted and A. Swinford, revised and reprinted 1986, Kansas Geological Survey, Educational Series 2, 64 p.


Mineral ID Table, p. 1 | Kansas Rocks

GeoKansas Home | KGS Home


Updated July 24, 2001
Please send comments to lbrosius@kgs.ku.edu
The URL is http://www.kgs.ku.edu/Extension/KGSrocks/table.html