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.
via Wikipedia infobox
{{Infobox mineral |boxbgcolor=#9c9471| name = Metacinnabar | boxtextcolor = #fff | image = Metacinnabar-233443.jpg | imagesize = 260px | alt = | caption = | category = Sulfide mineral | formula = HgS | IMAsymbol = Mcin | strunz = 2.CB.05a | dana = | system = Cubic | class = Hextetrahedral (3m) H-M symbol: ( 3m) | symmetry = F3m | 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 | density = | polish = | opticalprop = | refractive = | birefringence = | pleochroism = | 2V = | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = | alteration = | other = | references = | 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
}}
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).