|
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 + Fe2O3•nH2O
|
| 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 + Fe2O3•nH2O |
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 + Fe2O3•nH20 |
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 + Fe2O3•nH20 |
| 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, SiO2•nH20 |
| 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, SiO2•nH20 |
| 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
|