Number 17

Color--------------------White, colorless

Luster------------------Nonmetallic, glassy

Streak------------------White

Hardness--------------2.0

Cleavage/-------------Cleavage, 3 directions
Fracture

S.G.---------------------2.3 - 2.4

Special Properties---Known for flexibility.

Formula-----------------CaSo4   2H2O

Mineral Name---------Gypsum

Family-------------------Sulfates

Uses---------------------For plaster

Gypsum