fletcherite

{{Short description|Rare thiospinel sulfide mineral}}

{{about|the mineral|the followers of fletcherism|Horace Fletcher}}

{{infobox mineral

| name = Fletcherite

| image = File:Fletcherite.jpg

| alt = An image of a piece of fletcherite, a gray, metallic mineral

| caption =

| category = Sulfide mineral
Thiospinel group
Spinel structural group

| formula = {{chem2|Cu(Ni,Co)2S4}}

| IMAsymbol = Ftc{{Cite journal|last=Warr|first=L.N.|date=2021|title=IMA–CNMNC approved mineral symbols|journal=Mineralogical Magazine|volume=85|issue=3|pages=291–320|doi=10.1180/mgm.2021.43|bibcode=2021MinM...85..291W|s2cid=235729616|doi-access=free}}

| strunz = 2.DA.05

| dana =

| system = Cubic

| class = Hexoctahedral (m{{overline|3}}m)
H–M Symbol: (4/m {{overline|3}} 2/m)

| symmetry = Fd{{overline|3}}m

| unit cell = a = 9.520 Å; Z = 8

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| color = Steel gray, creamy white in polished section

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| habit = Minute subhedral to euhedral crystals typically enclosed within other sulfide minerals

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| mohs = 5

| luster = Metallic

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| diaphaneity = Opaque

| gravity = 4.76 calculated

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| polish = Good polish with moderate reflectivity

| opticalprop = Isotropic

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| references = [http://www.handbookofmineralogy.org/pdfs/fletcherite.pdf Handbook of Mineralogy][http://www.mindat.org/min-1557.html Mindat][http://webmineral.com/data/Fletcherite.shtml Webmineral data]{{cite journal|doi=10.2113/gsecongeo.72.3.480|title=Fletcherite, Cu(Ni,Co)₂S₄, a new thiospinel from the Viburnum Trend (New Lead Belt), Missouri|journal=Economic Geology|volume=72|issue=3|pages=480–486|date=1 May 1977|last1=Craig|first1=J. R.|last2=Carpenter|first2=A. B.|bibcode=1977EcGeo..72..480C }}

}}

Fletcherite is a rare thiospinel sulfide mineral with formula {{chem2|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.

It occurs as a dissemination within copper sulfide minerals in mineralization replacing dolomite 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.