Furutobeite

furutobeite

stromeyerite

bornite

digenite

Images

Formula: (Cu,Ag)6PbS4
Sulphide
Crystal System: Monoclinic
Specific gravity: 6.74 calculated
Hardness: 3
Colour: Grey
Environments

Hydrothermal environments

When heated, furutobeite decomposes at 100+/-2oC into galena plus a solid solution of CuAgS and Cu2S, which when cooled forms stromeyerite and chalcocite (AM 67.1075).
Associated minerals include stromeyerite, bornite, galena, sphalerite, tennantite, digenite and electrum (HOM).

Localities

At the type locality, the Furutobe mine, Kosaka, Akita Prefecture, Japan, furutobeite occurs in bornite-rich ore, as grains 10-300 microns, associated with bornite, stromeyerite, galena, sphalerite, tennantite, and sometimes digenite and electrum. It is replaced by stromeyerite (AM 67.1075).

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