17 mm square, 55 carat cerussite faceted by Duncan Miller from rough provided by Rockey Ollewagen

Cerussite is lead carbonate (PbCO3) and probably the best crystals come from Tsumeb. These can be large and glassy, usually clear, but sometimes grey, brown or red. It has a hardness of 3½; a specific gravity of 6,5; distinct cleavage in two directions; is very brittle and extremely heat sensitive. The refractive index is high, at 1,90 to 2,07; and the birefringence very strong. The dispersion is...

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