Grootfonteinite
A rare lead oxycarbonate from the Kombat mine in Namibia's Grootfontein district.
Intro adapted from Wikipedia (CC BY-SA).
Grootfonteinite is an IMA-recognized mineral species in the carbonate class, with the chemical formula Pb₃O(CO₃)₂.
It crystallizes in the hexagonal crystal system (space group P6_3mc).
Key properties: Mohs hardness 2; specific gravity 6.856; White streak; Adamantine luster.
IMA symbol Gtf, IMA status: approved, named in 2015.
A product of the regional metamorphism of a Pb-Mn-(As-Ba)-rich, chemically heterogeneous, volcanic-hydrothermal assemblage.
It is found associated with Jacobsite, cerussite, dolomite, clinochlore, hausmannite, melanotekite, sahlinite, rhodochrosite, barite.
The name refers to the Grootfontein district, in which the mine that provided the first specimens is located.