Alkaline feldspar

An alkaline feldspar is any of a number of common silicate minerals, most often found in whitish or colored glassy crystals.

Alkaline feldspars can be considered as mixtures of sodium aluminosilicates (NaAlSi3O8) and potassium aluminosilicates (KAlSi3O8). Both sodium and potassium aluminosilicates have different forms, each with its own structure.

Alkaline feldspars are used in the manufacture of glass and ceramics; being the transparent, colorful or iridescent varieties sometimes used as precious stones.

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