Metacinnabar

Cubic form of mercury sulfide

(repeating unit)HgSIMA symbolMcin^[1]Strunz classification2.CB.05aCrystal systemCubicCrystal classHextetrahedral (43m)
H-M symbol: (4 3m)Space groupF43mUnit cella = 5.8717(5) Å; Z = 4StructureJmol (3D)Interactive imageIdentificationColorGrayish blackCrystal habitMassive, rarely as tetrahedral crystals, as incrustationsTwinningCommon as lamellae on {111}CleavageNoneFractureSubconchoidalTenacityBrittleMohs scale hardness3LusterMetallicStreakBlackDiaphaneityOpaqueSpecific gravity7.7–7.8References^[2]^[3]^[4]

Metacinnabar is the cubic form of mercury sulfide (HgS). It is the high temperature form and trimorphous with cinnabar (trigonal structure) and the higher temperature hypercinnabar (hexagonal structure). It occurs with cinnabar in mercury deposits and is associated with native mercury, wurtzite, stibnite, marcasite, realgar, calcite, barite, chalcedony and hydrocarbons.^[2]

It was first described in 1870 for an occurrence in the Redington mine, Knoxville, Napa County, California.^[3]^[4]

References

Wikimedia Commons has media related to Metacinnabar.

^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
^ ^a ^b Metacinnabar in the Handbook of Mineralogy
^ ^a ^b Metacinnabar on Mindat.org
^ ^a ^b Metacinnabar data on Webmineral