Number 21

Color--------------------Peach

Luster------------------Nonmetallic, glassy to shiny

Streak------------------None - White (harder than a streak plate)

Hardness--------------6.0

Cleavage/--------------Cleavage, 2 good cleavages at 90
Fracture                    degrees

S.G.---------------------2.6

Special Properties---Most abundant of all minerals

Formula----------------KAlSi3O8

Mineral name---------Orthoclase

Family------------------Silicates

Uses--------------------Manufacture of glass and ceramics.

Orthoclase