Corderoite is an extremely rare mercury

sulfide Sulfide (British English also sulphide) is an inorganic anion of sulfur with the chemical formula S2− or a compound containing one or more S2− ions. Solutions of sulfide salts are corrosive. ''Sulfide'' also refers to chemical compounds la ...

chloride The chloride ion is the anion (negatively charged ion) Cl−. It is formed when the element chlorine (a halogen) gains an electron or when a compound such as hydrogen chloride is dissolved in water or other polar solvents. Chloride s ...

mineral with formula Hg₃S₂Cl₂. It crystallizes in the isometric crystal system. It is soft, 1.5 to 2 on the Mohs scale, and varies in color from light gray to black and rarely pink or yellow. It was first described in 1974 for occurrences in the McDermitt Mercury mine in

Humboldt County, Nevada Humboldt County is a county in the U.S. state of Nevada. As of the 2020 Census, the population was 17,285. It is a largely rural county that is sparsely populated with the only major city being Winnemucca which has a population of 8,431. Humb ...

. The name is from the old name of the mine, the ''Old Cordero Mine.''http://www.mindat.org/loc-4206.html Mindat McDermii Mine page

Structure

Corderoite has crankshaft chains that are crosswise linked by additional Hg²+. The bond distance between the cation Hg and anion S is 2.422 Angstroms. It has two angles, Hg-S-HG= 94.1º and S-Hg-S= 165.1º. Various sulfide halides of Hg share the feature of being face-sharing gS₂X₄−6 polyhedral, as corderoite's polyhedra X=Cl.

Geologic occurrence

The main occurrence of corderoite in the type locality is in the Upper

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...

playa sediments within a thick zone, around , sub parallel to bedding. Lake sediments including altered

rhyolitic Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture, but may be porphyritic, containing larger mineral crystals ( phenocrysts) in an otherwise fine-grained groundmass. The ...

tuff Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. Rock that contains greater than 75% ash is considered tuff, while rock ...

and

ash Ash or ashes are the solid remnants of fires. Specifically, ''ash'' refers to all non-aqueous, non-gaseous residues that remain after something burns. In analytical chemistry, to analyse the mineral and metal content of chemical samples, ash ...

were deposited on the Tertiary rhyolitic volcanic rocks. Corderoite occurs as isolated grains or with cinnabar as replacements. Corderoite occurs as a low temperature

supergene A supergene is a chromosomal region encompassing multiple neighboring genes that are inherited together because of close genetic linkage, i.e. much less recombination than would normally be expected. This mode of inheritance can be due to genom ...

mineral.Berendsen P., Foord E. E., and Storey L. O. (1974) "Corderoite, first natural occurrence of Hg₃S₂Cl₂, from the Cordero mercury deposit, Humboldt County, Nevada". ''American Mineralogist'', 59, 652–655 http://www.minsocam.org/ammin/AM59/AM59_652.pdf

References

{{Reflist *Grenchischev O. K. and Vasil'ev V. I. (1978) "First find of Corderoite (Hg₃S₂Cl₂) in mercury ores of USSR". Doklady. 246/1-6, 145. *Keller P., Lissner F., and Schleid T. (2005) "Single-crystal structure determination of Perroudite, Hg₅Ag₄S₅ (I,Br)₂Cl₂, from Tsumeb (Namiba), and its structural relationships to other sulfide halides of mercury and cinnabar." Stuttgart 181/1, 1–9. *Lavrent'ev Y. G. and Vasil'ev V. I. (1986) "New finds and data on the composition of corderoite (Hg₃S₂Cl₂)". ''Soviet Geology and Geophysics'', 27/12, 117–121. *Modreski P. J. (1998) "Eugene Edward Foord, 1946–1998". ''The Canadian Mineralogist'', 36/2, 251–254. Sulfide minerals Halide minerals Mercury(II) minerals Cubic minerals Minerals in space group 199