Black silvery acicular crystals of the rare PbCuBi sulphide pekoite from a little known locality (Germania Consolidated Mine, Turtle Lake, Stevens County, Washington, United States of America) on a contrasting matrix. — Photo: David Hospital · CC BY-SA 4.0
Pekoite
Pekoite is an IMA-recognized mineral species in the sulfosalt class, with the chemical formula CuPbBi₁₁S₁₈.
It crystallizes in the orthorhombic crystal system (space group P2_1am). It is a member of the Meneghinite structural group.
Key properties: specific gravity 6.8; Lead-gray streak; Metallic. R1 –R2: n.d luster.
IMA symbol Pek, IMA status: approved, named in 1975.
Found in magnetite pipes that cut felsic sediments and pyroclastics; the pipes are probably hydrothermal replacements in association with volcanism (Juno mine, Australia).
It is found associated with Gladite, junoite, emplectite, magnetite, chalcopyrite (Juno mine, Australia); paděraite, hammarite, chalcopyrite, grossular, andradite (Băiţa, Romania).
The name refers to the Peko mine, near the Juno mine, Tennant Creek, Australia.