metacinnabar

{{Short description|Cubic form of mercury sulfide}}

{{Infobox mineral

|boxbgcolor=#9c9471| name = Metacinnabar

| boxtextcolor = #fff

| image = Metacinnabar-233443.jpg

| imagesize = 260px

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| category = Sulfide mineral

| formula = HgS

| IMAsymbol = Mcin{{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.CB.05a

| dana =

| system = Cubic

| class = Hextetrahedral ({{overline|4}}3m)
H-M symbol: ({{overline|4}} 3m)

| symmetry = F{{overline|4}}3m

| unit cell = a = 5.8717(5) Å; Z = 4

| color = Grayish black

| habit = Massive, rarely as tetrahedral crystals, as incrustations

| twinning = Common as lamellae on {111}

| cleavage = None

| fracture = Subconchoidal

| tenacity = Brittle

| mohs = 3

| luster = Metallic

| streak = Black

| diaphaneity = Opaque

| gravity = 7.7–7.8

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| references = [http://rruff.info/doclib/hom/metacinnabar.pdf Metacinnabar in the Handbook of Mineralogy][http://www.mindat.org/min-2670.html Metacinnabar on Mindat.org][http://webmineral.com/data/Metacinnabar.shtml#.VGujBDS3sbg Metacinnabar data on Webmineral]

| SMILES = [SH+2]12[HgH2-2][SH+2]3[HgH2-2][SH+2]([HgH-2]14)[HgH-2]1[S+2]5([HgH-2]38)[Hg-2]26[SH+2]2[HgH-2]([S+2]4)[SH+2]1[HgH2-2][SH+2]3[HgH-2]2[S+2][HgH-2]([SH+2]6[HgH-2]([SH+2])[SH+2]68)[SH+2]([HgH2-2]6)[HgH-2]35

| Jmol = [SH+2]12[HgH2-2][SH+2]3[HgH2-2][SH+2]([HgH-2]14)[HgH-2]1[S+2]5([HgH-2]38)[Hg-2]26[SH+2]2[HgH-2]([S+2]4)[SH+2]1[HgH2-2][SH+2]3[HgH-2]2[S+2][HgH-2]([SH+2]6[HgH-2]([SH+2])[SH+2]68)[SH+2]([HgH2-2]6)[HgH-2]35

}}

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.

It was first described in 1870 for an occurrence in the Redington mine, Knoxville, Napa County, California.