Tables for identification of Kansas minerals
In the following pages are brief tables that may be useful in identifying Kansas minerals. So far as minerals from other states are concerned, the tables may be of no value and actually can be misleading. Therefore, published tables (such as those in Dana's Manual of Mineralogy) are strongly recommended for consultation for identification of any non-Kansas mineral.
Before attempting to identify minerals, the beginning collector should have on hand a small bottle of dilute hydrochloric (muriatic) acid, obtainable in any drugstore; a piece of unglazed porcelain, such as a small tile, for streak tests; an inexpensive steel pocketknife; a piece of ordinary window glass; and a chunk of quartz. A candle and a small pocket magnifier also are useful.
I. Metallic or sub metallic 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 | Yellow-brown (to dark-brown or black) | 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 non-crystalline | 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 non-crystalline | Limonite, FeO(OH) · nH2O + Fe2O3 · nH2O |
II. Nonmetallic luster
A. Colored streak
Streak | Color | Hardness | Remarks | Name, composition |
---|---|---|---|---|
Red-brown; "Indian 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 | 5-51/2 | Earthy to hard, with glassy luster. Seemingly noncrystalline | Limonite, FeO(OH) · nH2O + Fe2O3 · nH2O |
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)4O10(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)3AlSi3>O10(OH)2 | |
Yellowish-brown | 2 1/2-3 | As small scales or "books" with copperlike reflection from cleavage faces | Phlogopite mica, KMg3AlSi3O10(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 non- metallic minerals (differentiated from celestite). In sand-barite rosettes | Barite, BaSO4 |
White, blue, red | 3-31/2 | 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, bril- liant luster. Granular masses and platy crystals, associated with galena | Cerussite, PbCO3 |
Yellow | 3-31/2 | 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 · nH2O |
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, Zn4Sip7(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 · nH2O |
Gray, light-brown, cream, yellow, red, green | 7 | Waxy to dull luster. May be banded or lining cavitites. 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 |
Kansas Geological Survey
Placed on web Feb. 28, 2017; originally revised and reprinted 1998.
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