Minerals in the Recitation Rock Kits

There are two keys to learning how to identifying minerals and rocks: memorize their crucial diagnostic properties and see as many different examples as possible. This web page should help you with both!

Alphabetical List of Minerals



Physical Properties

(a mica)
Brown to brownish black; vitreous luster; H = 2.5 to 3.0; D = 2.8 to 3.2; may give a brown-gray streak; individual crystals are commonly small and cleavage surfaces are wavy; one perfect cleavage; transparent, flexible and elastic in thin sheets.
Clear, white, other colors less common; vitreous luster; H = 3; D = 2.7; three perfect cleavages form rhombohedric cleavage fragments; double image seen through clear pieces; reacts strongly with dilute hydrochloric acid.
Most commonly reddish brown or yellowish tan; vitreous to resinous luster; H = 6.5 to 7.5; D = 3.6 to 4.3; twelve-sided crystals (diamond-shaped faces) or roughly spherical crystals common. Broken surfaces may resemble cleavage in some large (> 1 cm) samples.
Clear to gray to red; H = 2.5; D = 2.2; three perfect cleavages meet at 90 degrees (cleavage surfaces may be dull and partially dissolved after prolonged exposure); salty taste.
Black; H = 5 to 6; D = 3.0 to 3.4; vitreous luster; may have faint green-gray streak; two perfect cleavages meet at 124 degrees and 56 degrees, but cleavage faces are commonly stepped rather than smooth; splintery appearance. An amphibole mineral.
Salmon-pink, white, gray, green; vitreous luster; H = 6; D = 2.5 to 2.6; two cleavages meet at nearly 90 degrees; no striations.
Colorless, silvery white, brownish silvery white; vitreous luster; H = 2.0 to 2.5; D = 2.8 to 2.9; one perfect cleavage; transparent, flexible, and elastic in thin sheets.
Olive-green to yellow green; vitreous to dull luster; H = 6.5 to 7 but often difficult to test because many samples are granular aggregates.
White to dark gray; sometimes buff; vitreous luster; H = 6; D = 2.6 to 2.8; two cleavages meet at nearly 90 degrees; some cleavage faces have very fine, perfectly straight parallel striations, which show up in reflected light.
Brass-yellow; H = 6 to 6.5; D = 5.0; greenish black to black streak; massive or as crystals (cubes or pyritohedra).
Coarsely crystalline varieties: clear, milky, white, purple, smokey gray; pink; transparent to translucent; vitreous luster; H = 7; D = 2.7; conchoidal fracture; usually massive but six-sided crystals popular in rock shops.

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