Cerussite (lead carbonate)
Color: Colorless, yellowish, gray and brown.
Moh’s hardness: 3.5
Refractive index: 1.804-2.078
Critical angle: 31.5°
Specific gravity: 6.46-6.57
Cleavage: Perfect in 2 directions.
Fracture: Conchoidal, uneven, very brittle.
Dispersion: Very strong (.051)
Heat sensitivity: Very high
Birefringence (double refraction): Very strong (.274)
Crystal structure: Orthorhombic
Cutting: Watch out for cleavage plane. Sharp corners tend to chip.
Polishing: Alumina on wax lap or chrome oxide Ultralap.
Comments: Use adhesives for dopping.