tremolite

{{Infobox mineral | name = Tremolite | boxwidth = | boxbgcolor = | image = Tremolite Campolungo.jpg | imagesize = 300px | alt = | caption = | category = Inosilicates | formula = Ca2(Mg5.0-4.5Fe2+0.0-0.5)Si8O22(OH)2 | IMAsymbol = Tr | molweight = | strunz = 9.DE.10 | dana = | system = Monoclinic | class = Prismatic (2/m) (same H-M symbol) | symmetry = C2/m (no. 12) | unit cell = a = 9.84 Å, b = 18.02 Å c = 5.27 Å; β = 104.95°; Z = 2 | color = White, gray, lavender to pink, light green, light yellow | colour = | habit = Elongated prismatic, or flattened crystals; also as fibrous, granular or columnar aggregates | twinning = Simple or multiple, common parallel to {100}; rarely parallel to {001} | cleavage = Perfect on {110} at 56° and 124°; partings on {010} and {100} | fracture = | tenacity = Brittle | mohs = 5–6 | luster = Vitreous and silky | streak = White | diaphaneity = Transparent to translucent | gravity = 2.99–3.03 | density = | polish = | opticalprop = Biaxial (−) | refractive = nα = 1.599 – 1.612 nβ = 1.613 – 1.626 nγ = 1.625 – 1.637 | birefringence = δ = 0.026 | pleochroism = | 2V = Measured: 86° to 88° | dispersion = | extinction = | length fast/slow = | fluorescence = Short UV=yellow, Long UV=pink | absorption = | melt = | fusibility = | diagnostic = | solubility = | impurities = | alteration = | other = | references = }}

Tremolite is a member of the amphibole group of silicate minerals with composition Ca2(Mg5.0-4.5Fe2+0.0-0.5)Si8O22(OH)2. Tremolite forms by metamorphism of sediments rich in dolomite and quartz, and occurs in two distinct forms, crystals and fibers. Tremolite forms a series with actinolite and ferro-actinolite. Pure magnesium tremolite is creamy-white, but the color grades to dark green with increasing iron content. It has a hardness on Mohs scale of 5 to 6. Nephrite, one of the two minerals known as the gemstone jade, is a green crystalline variety of tremolite.