Cassiterite (tin oxide)
Color: brown, yellowish-brown and colorless.
Moh’s hardness: 6-7
Refractive index: 1.997-2.101
Critical angle: 29°
Specific gravity: 6.8-7.1
Fracture: Conchoidal to subconchoidal, brittle.
Dispersion: Very strong (.071)
Heat sensitivity: None
Pleochroism: Dichroic – Definite.
Birefringence (double refraction): Strong (.096)
Crystal structure: Tetragonal
Cutting: Cutting is fairly straightforward.
Polishing: Most common polishing laps with alumina or tin oxide Ultralap.
Comments: Polishing takes a long time.