vaterite

{{Infobox mineral | name = Vaterite | boxwidth = | boxbgcolor = | image = Vaterite2-San Vito, Monte Somma, Italy.tif | imagesize = | alt = | caption = Vaterite from San Vito quarry, San Vito, Monte Somma, Somma-Vesuvius Complex, Italy | category = Carbonate minerals | formula = CaCO3 | IMAsymbol = Vtr | molweight = | strunz = 5.AB.20 | dana = | system = Hexagonal | class = Dihexagonal dipyramidal (6mmm) H-M symbol: (6/m 2/m 2/m) | symmetry = P63/mmc {P63/m 2/m 2/c} | unit cell = a = 4.13, c = 8.49 [Å]; Z = 6 | color = Colorless | colour = | habit = Fine fibrous crystals, typically less than 0.1 mm, in spherulitic aggregates. | twinning = | cleavage = | fracture = Irregular to uneven, splintery | tenacity = Brittle | mohs = 3 | luster = Sub-vitreous, waxy | streak = | diaphaneity = Transparent to semi-transparent | gravity = 2.54 | density = | polish = | opticalprop = Uniaxial (+) | refractive = nω = 1.550 nε = 1.650 | birefringence = δ = 0.100 | pleochroism = | 2V = | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = | alteration = | other = | prop1 = | prop1text = | references = }}

Vaterite is a mineral, a polymorph of calcium carbonate (CaCO3). It was named after the German mineralogist Heinrich Vater. It is also known as mu-calcium carbonate (μ-CaCO3). Vaterite belongs to the hexagonal crystal system, whereas calcite is trigonal and aragonite is orthorhombic.