Microcline (Var. Amazonite)
Lake George, Colorado

These two crystals measure 6.5cm x 5.5cm in height


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:The specimens shown above display albite epitaxial overgrowth.

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

Note: Specimen collected by Lance E. Kearns, 1970

Photo by Mary Sutherland


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