glauberite

{{Infobox mineral | name = Glauberite | image = Glauberite-172284.jpg | alt = | caption = Glauberite crystal group from the Bertram Siding Sulfate deposit, Imperial County, California | category = Sulfate minerals, anhydrous sulfate subgroup | formula = Na2Ca(SO4)2 | IMAsymbol = Glb | strunz = 7.AD.25 | dana = | system = Monoclinic | class = Prismatic (2/m) (same H-M symbol) | symmetry = C2/c | unit cell = a = 10.129, b = 8.306 c = 8.533 [Å]; β = 112.19°; Z = 4 | color = Gray or pale yellow, colorless | colour = | habit = Tabular prismatic crystals | twinning = | cleavage = Perfect on {001}, imperfect on {110} | fracture = Conchoidal | tenacity = Brittle | mohs = 2.5–3 | luster = Vitreous to waxy, pearly on cleavages | streak = White | diaphaneity = Transparent to translucent | gravity = 2.75–2.85 | density = | polish = | opticalprop = Biaxial (−) | refractive = nα = 1.507 – 1.515 nβ = 1.527 – 1.535 nγ = 1.529 – 1.536 | birefringence = δ = 0.022 | pleochroism = | 2V = 24° to 34° | dispersion = strong r > v | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = HCl and H2O (water) soluble | impurities = | alteration = readily alters to gypsum | other = often a pseudomorph | prop1 = | prop1text = | references = }}

Glauberite is a monoclinic sodium calcium sulfate mineral with the formula Na2Ca(SO4)2.