Mineralpedia Details for Anorthoclase

Formula

(Na,K)AlSi₃O₈ 

Crystal System

Triclinic 

Crystal Habit

Disseminated, Granular 

Cleavage

Perfect, Good, None 

Luster

Vitreous (Glassy) 

Color

colorless, green, gray, gray pink, yellow 

Streak

white 

Class

Triclinic - Pinacoidal 

Fracture

Uneven 

Hardness

6 

WebMineral

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Mindat

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Compact, tight dark crystals to 1cm in gabbro, a typical association. Anorthoclase is a variety of feldspar intermediate between Sanidine (K) and Albite (Na). The feldspar group is actually a ternary system with Na - Ca - K at the corners.