Outstanding platy silvery crystals of the very rare sulphosalt mineral playfairite from Austin, Lander County, Nevada, United States of America. Ex Vandenbroucke Museum collection from Waregem, Belgium. — Photo: David Hospital · CC BY-SA 4.0
Playfairite
A rare monoclinic lead-antimony sulfosalt discovered in 1966, named for Scottish mathematician John Playfair.
Intro adapted from Wikipedia (CC BY-SA).
Playfairite is an IMA-recognized mineral species in the sulfosalt class, with the chemical formula Pb₁₆(Sb,As)₁₉S₄₄Cl.
It crystallizes in the monoclinic crystal system. It is a member of the Madocite structural group.
Key properties: specific gravity 5.72; Black streak; Metallic luster.
IMA symbol Pyf, IMA status: approved, named in 1966.
Occurs as masses and stringers through dolomitic and calcitic marbles. At the edges of other sulfosalt minerals, and extending into them along microscopic veinlets.
It is found associated with Boulangerite, jamesonite, antimonian baumhauerite, zinkenite, semseyite, geocronite, robinsonite, madocite, launayite (Madoc, Canada); sphalerite, pyrite.
In honor of John Playfair (1748–1819), Professor of Natural Philosophy, Edinburgh, Scotland.