Number 22

Color--------------------White with brown marks

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

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

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

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

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

Special Properties----Occurs in numerous mineral enviroments.

Formula----------------(Na,Ca)Al1Si3O8

Mineral name---------Plagioclase

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

Uses--------------------Ceramics

Plagioclase