Wulfenite
(lead molybdate)
Color: orange, red, yellow and colorless.
Moh’s hardness: 2.5-3
Refractive index: 2.3
Critical angle: 25.5°
Specific gravity: 7
Cleavage: Distinct in one direction.
Fracture: Uneven, very brittle.
Dispersion: Strong
Heat sensitivity: Extremely high.
Birefringence (double refraction): Very
strong (.122)
Crystal structure: Tetragonal.
Cutting: The brittle nature of wulfenite
makes it very difficult to cut. Use an extra fine lap and protect the stone from
any kind of shock. Adhesives are essential for dopping.
Polishing: Alumina or tin oxide on wax lap.
The trailing end of the facet tends to round over.
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