Microcline (Var. Amazonite)
Lake George, Colorado

This specimen measures 10cm x 8cm


Microcline     KAlSi3O8

Tectosilicate; potassium aluminum silicate, sometimes with considerable amounts of sodium

Color and Luster: White, pink, brown, gray, blue, green, colorless, yellowish; vitreous, streak white

Hardness: 6-6.5

Cleavage: Good, two directions at 90°

Fracture: Uneven

Crystals: Triclinic; predominantly as single crystals of rectangular or square cross section and as tabular crystals; twin crystals very common; also cleavage masses, granular, disseminated grains

Note: Orthoclase, sanadine, adularia, and microcline are the potash feldspars Andularia is often called moonstone, with a transparent or opalescent appearance Sanadine is glassy, Microcline is white to pale yellow, rarely red, and when bright green or blue it is called amazonite

Photo by Mary Sutherland


Descriptions taken from
The Audubon Society Field Guide to North American Rocks and Minerals