Sweetite has a general formula of Zn(OH)2.[ The name is given after a curator of mineral department of the British Museum, Jessie May Sweet (1901–1979).][Ralph, Jolyon. "Sweetite" Mindat.org. 2010. 17 Sep 2010] It occurs in an oxidized vein in limestone bedrock with galena, ashoverite, wülfingite, anglesite, cerussite, hydrocerussite, litharge, fluorite, palygorskite and calcite.[
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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.[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.] 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.[Ralph, Jolyon. "Sweetite" Mindat.org. 2010. 7 Nov 2010] 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.["Sweetite" (http://webmineral.com/data/Sweetite.shtml). Mineral Data. http://webmineral.com/data/Sweetite.shtml. Retrieved 7 November 2010.] 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.[
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Sweetite is mostly found from a limestone quarry 200–300 m northwest of Milltown, near Ashover, Derbyshire, England.[
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