kieserite

{{Infobox mineral | name = Kieserite | category = Sulfate minerals | boxwidth = | boxbgcolor = | image = Kieseriet (Kieserite).jpg | imagesize = 260px | caption = | formula = MgSO4·H2O | IMAsymbol = Ksr | strunz = 7.CB.05 | dana = 29.6.2.1 | system = Monoclinic | class = Prismatic (2/m) (same H-M symbol) | symmetry = C2/c | unit cell = a = 7.51 Å, b = 7.61 Å c = 6.92 Å; β = 116.17°; Z = 4 | color = Colorless, grayish-white or yellowish | habit = Massive, granular; rarely as pyramidal crystals | twinning = Contact on {001}, polysynthetic about [110] | cleavage = {110} and {111} perfect | fracture = Uneven | tenacity = Fragile | mohs = 3.5 | luster = Vitreous to dull | streak = White | diaphaneity = Transparent to translucent | gravity = 2.57 | density = | polish = | opticalprop = Biaxial (+) | refractive = nα = 1.520 nβ = 1.533 nγ = 1.584 | birefringence = δ = 0.064 | pleochroism = | 2V = 55° | dispersion = r > v, moderate | extinction = | length fast/slow = | fluorescence= | absorption = | melt = | fusibility = | diagnostic = | solubility = In water | other = | alteration = | references = }}

Kieserite, or magnesium sulfate monohydrate, is a hydrous magnesium sulfate mineral with formula (MgSO4·H2O).