Plumbogummite Locality: Yangshuo Mine, Yangshuo County , Guilin Prefecture, Guangxi Zhuang Autonomous Region , China ( Locality at mindat.org ) Size: small cabinet, 7.7 x 4.4 x 4 cm PLUMBOGUMMITE A superb small cabinet plumbogummite specimen, for its rich color, completeness all around, and 3-dimensional form. It is a rich specimen with a velvety look to it. Very nice "fingers" representing mimetite crystals that are coated, and partially pseudomorphed, to plumbogummite. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Plumbogummite
A rare secondary lead-aluminium phosphate of the crandallite subgroup, forming botryoidal crusts.
Intro adapted from Wikipedia (CC BY-SA).
Plumbogummite is an IMA-recognized mineral species in the phosphate class, with the chemical formula PbAl₃(PO₄)(PO₃OH)(OH)₆.
It crystallizes in the hexagonal crystal system (space group R-3m). It is a member of the Alunite-crandallite structural group.
Key properties: Mohs hardness 4.5–5; specific gravity 4.01; White streak; Vitreous, resinous to dull luster; optically uniaxial.
IMA symbol Pbg, IMA status: approved, named in 1819.
Occurs as an uncommon secondary mineral in the oxidized zone of lead deposits.
It is found associated with Pyromorphite, mimetite, duftite, cerussite, anglesite, wulfenite.
The name comes from the Latin for lead and gum, which it may resemble.