Pillaite

Pillaite is a very rare mineral known from only one locality worldwide, the famous Buca della Vena mine in Italy, which is of course the type locality. It occurs as outstanding acicular metallic crystals in a white contrasting dolomitic limestone matrix. — Photo: David Hospital · CC BY-SA 4.0

Pillaite

Pillaite is an IMA-recognized mineral species in the halide class, with the chemical formula Pb₉Sb₁₀S₂₃ClO₀.₅.

It crystallizes in the monoclinic crystal system (space group C2/m).

Key properties: specific gravity 5.77; Black to dark brown, rare red internal reflections in reflec streak; Metallic luster.

IMA symbol Pil, IMA status: approved, named in 1997.

Result of complex sulfide deposition by hydrothermal brines, at relatively high temperatures and fO2/fS2 conditions controlled by the pyrite-hematite-magnetite buffer.

It is found associated with Sphalerite, cinnabar, galena, tetrahedrite, chalcostibite, gersdorffite, baryte, boulangerite, robinsonite, scainiite, zinkenite, tintinaite, sorbyite.

The mineral was named to honor Italian vulcanologist and mineralogist, Professor Leopoldo Pilla (1805-1848).