Cerussite, lead carbonate,
Formula PbCO₃.

Crystal system: Orthorhombic (crystal form usually tabular, hexagonal bipyramids or acicular).
Hardness: 3 to 3.5
Density: 6.4 to 6.6 gms/cm³
Colour: Colourless, white, yellow, grey, brown or black.
Streak: White.

Cerussite is a common supergene mineral formed in the oxydation zones of lead deposits. It is produced by reaction between carbon dioxide and galena (lead�sulphide) with which it commonly occurs. Really fine lustrous crystalline specimens were found at Tsumeb in Namibia.

The specimen shown in the picture came from Tsumeb, Namibia, South West Africa.