Hydrocerussite , Cerussite Locality: Tsumeb Mine (Tsumcorp Mine), Tsumeb , Otjikoto (Oshikoto) Region, Namibia ( Locality at mindat.org ) Size: 10.1 x 9.7 x 4.3 cm. A fine example of reticulated Cerussite with large, well developed bladed crystals coated with a chalky, stark white layer of Hydrocerussite (actually, it is probably just starting the process of truly pseudomorphing into the hydrocerussite and that layer is probably an alteration rather than a coating). Ex. Willy Israel Collection. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Hydrocerussite
Natural basic lead carbonate — the mineral form of white-lead pigment, a hydrate companion of cerussite.
Intro adapted from Wikipedia (CC BY-SA).
Hydrocerussite is an IMA-recognized mineral species in the carbonate class, with the chemical formula Pb₃(CO₃)₂(OH)₂.
It crystallizes in the hexagonal crystal system (space group R-3m).
Key properties: Mohs hardness 3.5; specific gravity 6.8–6.82; Adamantine, pearly on {0001} luster; optically uniaxial.
IMA symbol Hcer, grandfathered status — known before the IMA’s founding, named in 1877.
Occurs as an uncommon secondary mineral in the oxidized portions of lead deposits.
It is found associated with Lead (Långban, Sweden); cerussite, leadhillite, matlockite, paralaurionite, diaboleite, leadhillite, galena (Mammoth-St. Anthony mine, Arizona, USA).
In allusion to the essential chemical components, water and the lead and carbonate of cerussite.