Sterryite, a silver lead sulphosalt, is a very rare mineral present only in two localities worldwide, being this one in Apuan Alps the best by far. From: Pollone Mine, Valdicastello Carducci, Lucca, Tuscany, Italy. — Photo: David Hospital · CC BY-SA 4.0
Sterryite
Sterryite is an IMA-recognized mineral species in the sulfosalt class, with the chemical formula Cu(Ag,Cu)₃Pb₁₉(Sb,As)₂₂(As)₂S₅₆.
It crystallizes in the monoclinic crystal system (space group P2_1/n). It is a member of the Madocite structural group.
Key properties: Mohs hardness 3.5; specific gravity 5.91; Black streak; Metallic luster.
IMA symbol Srr, IMA status: approved, named in 1966.
Of hydrothermal origin, in marble.
It is found associated with Veenite, guettardite.
The mineral was named to honor Thomas Sterry Hunt (1826–1892), first mineralogist with the Geological Survey of Canada, Ottawa, Canada.