{{Infobox mineral | name = Sweetite | category = Hydroxide mineral | boxwidth = | boxbgcolor = | image = | imagesize = | caption = | formula = Zn(OH)<sub>2</sub> | IMAsymbol = Sw<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> | molweight = 99.40 g/mol | strunz = 4.FA.10 | system = Tetragonal <br/>Unknown space group | class = Trapezohedral (422) <br/>H-M symbol: (422) | symmetry = ''P4<sub>1</sub>2<sub>1</sub>2'' (no. 92) or ''P4<sub>3</sub>2<sub>1</sub>2'' (no. 96) | unit cell = a = 8.22, c = 14.34 [Å] <br/>V = 968.93 Å<sup>3</sup>; Z = 20 | color = Colorless, white | habit = Bipyramidal | twinning = | cleavage = None | fracture = Irregular | tenacity = | mohs = 3 | luster = Vitreous | refractive = n<sub>ω</sub> = 1.635 n<sub>ε</sub> = 1.628 | opticalprop = Uniaxial (−) | birefringence = 0.007 | pleochroism = | streak = White | gravity = 3.33 | density = | melt = | fusibility = | diagnostic = | solubility = | diaphaneity = Transparent to translucent | other = | references = <ref name=Webmin>[http://webmineral.com/data/Sweetite.shtml Webmineral data]</ref><ref name=Mindat>[http://www.mindat.org/min-3846.html Mindat.org]</ref><ref>[http://www.mineralienatlas.de/lexikon/index.php/MineralData?mineral=Sweetit Mineral Atlas]</ref><ref name=HBM>[http://rruff.geo.arizona.edu/doclib/hom/sweetite.pdf Handbook of Mineralogy]</ref> }} '''Sweetite''' has a general formula of Zn(OH)<sub>2</sub>.<ref name=Webmin/> The name is given after a curator of mineral department of the British Museum, Jessie May Sweet (1901–1979).<ref>Ralph, Jolyon. "Sweetite" Mindat.org. 2010. 17 Sep 2010</ref> It occurs in an oxidized vein in limestone bedrock with galena, ashoverite, wülfingite, anglesite, cerussite, hydrocerussite, litharge, fluorite, palygorskite and calcite.<ref name=HBM/>
Sweetite is tetragonal, which means crystallographically it contains one axis of unequal length and two axes of equal length. The angles between three of the axes are all 90°. It belongs to the space group 4/m. Some crystals show evidence of a basal plane and a few are tabular.<ref>Clark, A.M., Fejer, E.E., Couper, A.G., and Jones G.C. (1984) Sweetite, a new mineral from Derbyshire. Mineralogical Magazine, 48, 267–269.</ref> In terms of its optical properties, sweetite has two indices of refraction, 1.635 along the ordinary ray and 1.628 along the extraordinary ray.<ref>Ralph, Jolyon. "Sweetite" Mindat.org. 2010. 7 Nov 2010</ref> The index of refraction is the velocity of light in vacuum divided by the velocity of light in medium. It also has the birefringence of 0.007.<ref>"Sweetite" (http://webmineral.com/data/Sweetite.shtml). Mineral Data. http://webmineral.com/data/Sweetite.shtml. Retrieved 7 November 2010.</ref> The birefringence means the decomposition of light into two rays when passing through a mineral. Sweetite is 1.64–1.65 in relief, which is medium to high in intensity and means a measure of the relative difference between the index of refraction of a mineral and its surrounding medium.<ref name=Webmin/>
Sweetite is mostly found from a limestone quarry 200–300 m northwest of Milltown, near Ashover, Derbyshire, England.<ref name=HBM/>
== References == {{Reflist}}
Category:Hydroxide minerals Category:Zinc minerals Category:Tetragonal minerals Category:Minerals in space group 92 Category:Minerals in space group 96 Category:Minerals described in 1983
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