Fletcherite

This article is about the mineral. For the followers of fletcherism, see Horace Fletcher.
Fletcherite
General
Category Sulfide mineral
Thiospinel group
Spinel structural group
Formula
(repeating unit)
Cu(Ni,Co)2S4
Strunz classification 2.DA.05
Crystal system Cubic
Crystal class Hexoctahedral (m3m)
H–M Symbol: (4/m 3 2/m)
Space group Fd3m
Unit cell a = 9.520 Å; Z = 8
Identification
Color Steel gray, creamy white in polished section
Crystal habit Minute subhedral to euhedral crystals typically enclosed within other sulfide minerals
Mohs scale hardness 5
Luster Metallic
Diaphaneity Opaque
Specific gravity 4.76 calculated
Polish luster Good polish with moderate reflectivity
Optical properties Isotropic
References [1][2][3][4]

Fletcherite is a rare thiospinel sulfide mineral with formula Cu(Ni,Co)2S4. It is an opaque metallic steel gray mineral which crystallizes in the cubic crystal system. It is a member of the linnaeite group.

It was first described in 1977 for an occurrence in the Fletcher Mine, Viburnum Trend (New Lead Belt), near Centerville, Reynolds County, Missouri.[2][1]

It occurs as a dissemination within copper sulfide minerals in mineralization replacing dolostone at the type locality in the Fletcher mine where it is associated with vaesite, pyrite, covellite, chalcopyrite, bornite and digenite. In an occurrence in Kalgoorlie, Australia it is found in black slate associated with pyrrhotite.[1]

References

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