arcanite

{{infobox mineral | name = Arcanite | image = Arcanite.jpg | imagesize = 260px | alt = | caption = Arcanite | category = Sulfate mineral | formula = K2SO4 |IMAsymbol=Acn | molweight = | strunz = 7.AD.05 | dana = | system = Orthorhombic | class = Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m) | symmetry = Pmcn | unit cell = a = 5.77, b = 10.07 c = 7.48 [Å]; Z = 4 | color = White to colorless, yellow | colour = | habit = Tabular crystals, typically in crusts and coatings | twinning = Cyclic on {110} | cleavage = Good on {010} and {001} | fracture = | tenacity = | mohs = 2 | luster = Vitreous | streak = White | diaphaneity = Transparent to translucent | gravity = 2.66 | density = | polish = | opticalprop = Biaxial (+) | refractive = nα = 1.494 nβ = 1.495 nγ = 1.497 | birefringence = δ = 0.004 | pleochroism = | 2V = Measured: 67° | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = | alteration = | other = | references = }} Arcanite is a potassium sulfate mineral with formula K2SO4.

Arcanite was first described in 1845 for an occurrence in old pine railroad ties in the Santa Ana tin mine, Trabuco Canyon, Santa Ana Mountains, Orange County, California, US. It has also been reported from hydrothermal deposits in the Cesano geothermal field, Latium, Italy; in bat guano on the Chincha Islands of Peru; and in caves in Western Australia, South Africa and Namibia.