vesuvianite

{{Infobox mineral | boxbgcolor = #747827 | boxtextcolor = #fff | name = Vesuvianite | category = Sorosilicate | image = Vesuvianite-242685.jpg | alt = | caption = Vesuvianite from the Jeffrey Mine in Val-des-Sources, Quebec | formula = Ca10(Mg, Fe)2Al4(SiO4)5(Si2O7)2(OH,F)4 | IMAsymbol = Ves | strunz = 9.BG.35 | system = Tetragonal | class = Ditetragonal dipyramidal (4/mmm) H-M symbol: (4/m 2/m 2/m) | symmetry = P4/nnc | unit cell = a = 15.52 Å, c = 11.82 Å Z = 2 | color = Yellow, green, brown; colorless to white, brown-black, light green, emerald green, violet, blue-green to blue, pink, purple, red, black, commonly zoned | habit = Short pyramidal to long prismatic crystals common, massive to columnar | twinning = Fine twin domains observed | cleavage = Poor on {110} and {100} very poor on {001} | fracture = Sub conchoidal to irregular | tenacity = Brittle | mohs = 6–7 | luster = Vitreous to resinous | refractive = nω = 1.703–1.752nε = 1.700–1.746 | opticalprop = Uniaxial (−) | birefringence = 0.004–0.006 | pleochroism = slight in colored varieties | streak = White | gravity = 3.32–3.43 | density = | melt = | fusibility = | diagnostic = | solubility = Vesuvianite is virtually insoluble in acids | diaphaneity = Subtransparent to translucent | other = striated lengthwise | references = }}

Vesuvianite, also known as idocrase, is a green, brown, yellow, or blue silicate mineral. Vesuvianite occurs as tetragonal crystals in skarn deposits and limestones that have been subjected to contact metamorphism. It was first discovered within included blocks or adjacent to lavas on Mount Vesuvius, hence its name. Attractive-looking crystals are sometimes cut as gemstones. Localities which have yielded fine crystallized specimens include Mount Vesuvius and the Ala Valley near Turin, Piedmont.