{{Short description|Native element mineral}} {{Infobox mineral | name = Rosickyite | boxwidth = | boxbgcolor = | image = Rosickýite.jpg | imagesize = | alt = | caption = Sharp yellow crystals of rosickyite on matrix from an unspecified off shore drill hole in the Pacific Ocean near California (Ventura County, California, United States of America). | category = Native element mineral | molweight = | formula = S | IMAsymbol = Rký<ref>{{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}}</ref> | strunz = 1.CC.05 | dana = | system = Monoclinic | class = Prismatic (2/m) <br/><small>(same H-M symbol)</small> | symmetry = ''P2/c'' | unit cell = a = 8.455(3)&nbsp;Å, <br/>b = 13.052(2)&nbsp;Å <br/>c = 9.267(3)&nbsp;Å; <br/>β = 124.89(3)°; Z&nbsp;=&nbsp;4 | color = Colorless to pale yellow, green tinge | colour = | habit = Equidimensional to thin tabular crystals, efflorescences | twinning = On {101}, with twin lamellae parallel to [010] | cleavage = None | fracture = | tenacity = | mohs = 2 - 3 | luster = Adamantine | streak = | diaphaneity = Transparent to translucent | gravity = 2.07 | density = | polish = | opticalprop = Biaxial (-) | refractive = | birefringence = | pleochroism = | 2V = | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = | alteration = | other = | references = <ref name=HBM>[http://rruff.geo.arizona.edu/doclib/hom/rosickyite.pdf Handbook of Mineralogy]</ref><ref name=Mindat>[http://www.mindat.org/min-3458.html Rosickyite on Mindat.org]</ref><ref name=Webmineral>[http://webmineral.com/data/Rosickyite.shtml#.UEykObJmReo Rosickyite on Webmineral.com]</ref> }} '''Rosickyite''' is a rare native element mineral that is a polymorph of sulfur. It crystallizes in the monoclinic crystal system and is a high temperature, high density polymorph. It occurs as soft, colorless to pale yellow crystals and efflorescences.<ref name=HBM/><ref name=Mindat/>

It was first described in 1930 for an occurrence in Havirna, near Letovice, Moravia, Czech Republic. It was named for Vojtĕch Rosický (1880–1942), of Masaryk University, Brno.<ref name=HBM/><ref name=Mindat/>

Rosickyite occurs as in Death Valley within an evaporite layer produced by a microbial community. The otherwise unstable polymorph was produced and stabilized within a cyanobacteria dominated layer.<ref>Susanne Douglas and Heixong Yang, ''Mineral biosignatures in evaporites: Presence of rosickyite in an endoevaporitic microbial community from Death Valley, California,'' Geology, Dec. 2002, v 30, pp1075-1078</ref>

==References== {{Reflist}}

{{DEFAULTSORT:Rosickyite}} Category:Native element minerals Category:Monoclinic minerals Category:Minerals in space group 13 Category:Sulfur Category:Polymorphism (materials science)