Selenite
(gypsum)
Color: Colorless
Moh’s hardness: 2
Refractive index: 1.52
Critical angle: 41°
Specific gravity: 2.3-2.33
Cleavage: Perfect in 1 direction and strong
in 2 directions.
Fracture: Extremely splintery
Dispersion: None
Heat sensitivity: High
Pleochroism: None
Birefringence (double refraction): Weak
(.009)
Crystal structure: Monoclinic
Cutting: Cleavage is so strong that it will
split apart during sawing and performing. Extra-fine laps should be used at all
cutting stages.
Polishing: Wax lap with alumina at slow
speed.
Comments: Only use adhesives for
dopping. Selenite is one of the most challenging of all stones to facet.
If you are a
glutton for punishment, this one’s for you.
OPAL Server
|