Tiemannite

{{Infobox mineral

| name = Tiemannite

| category = Selenide mineral

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| image = Tiemannit.jpg

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| formula = HgSe

| IMAsymbol = Tmn{{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 = 02.08.02.04

| molweight =

| color = Steel-gray to black

| habit = Massive and as euhedral crystals

| system = Isometric

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

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

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| cleavage = none

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| mohs = 2.5

| luster = Metallic

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| streak = grayish black

| gravity = 8.19–8.47

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| diaphaneity = opaque

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| references = [http://webmineral.com/data/Tiemannite.shtml Tiemannite Mineral Data][http://www.mindat.org/min-3957.html Tiemannite: Tiemannite mineral information and data]

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Tiemannite is a mineral, mercury selenide, formula HgSe. It occurs in hydrothermal veins associated with other selenides, or other mercury minerals such as cinnabar, and often with calcite. Discovered in 1855 in Germany, it is named after Johann Carl Wilhelm Tiemann (1848–1899).