wiluite

{{Infobox mineral | name = Wiluite | boxwidth = | boxbgcolor = | image = Wiluite-rh3-48b.jpg | imagesize = 260 | alt = | caption = Wiluite crystal from the Wilui River, Siberia | category = Sorosilicates | formula = | IMAsymbol = Wil | molweight = | 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 = 15.716, c = 11.704 [Å]; Z = 2 | color = Dark green | colour = | habit = Typically as euhedral crystals | twinning = | cleavage = {100} poor | fracture = Irregular | tenacity = | mohs = 6 | luster = Vitreous | streak = | diaphaneity = | gravity = 3.36 | density = | polish = | opticalprop = Uniaxial (+) | refractive = nω = 1.721 nε = 1.725 | birefringence = δ = 0.004 | pleochroism = | 2V = | dispersion = | extinction = | length fast/slow = | fluorescence = | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = | alteration = | other = | prop1 = | prop1text = | references = }}

Wiluite is a dark green, brownish, or black blocky silicate mineral with the chemical formula . It has a Mohs hardness of 6 and a specific gravity of 3.36. It has a vitreous lustre, poor cleavage and an irregular brittle fracture. It crystallizes in the tetragonal system and occurs as well-formed crystals with good external form. It is isostructural with the vesuvianite group and is associated with wollastonite and olive-green grossulars (viluites) in a serpentinized skarn.