zircon

{{Infobox mineral |boxbgcolor=#b56042| name = Zircon | boxtextcolor = #fff | category = Nesosilicates | image = Zircon-dtn1a.jpg | imagesize = 260px | caption = A lustrous crystal of zircon perched on a tan matrix of calcite from the Gilgit District of Pakistan | formula = zirconium silicate  | IMAsymbol = Zrn | molweight = | strunz = 9.AD.30 | system = Tetragonal | class = Ditetragonal dipyramidal (4/mmm) H-M symbol: (4/m 2/m 2/m) | symmetry = I41/amd (No. 141) | unit cell = a = 6.607(1), c = 5.982(1) [Å]; Z = 4 | color = Reddish brown, yellow, green, blue, gray, colorless; in thin section, colorless to pale brown | habit = tabular to prismatic crystals, irregular grains, massive | twinning = On {101}. Crystals shocked by meteorite impact show polysynthetic twins on {112} | cleavage = {110} and {111} | fracture = Conchoidal to uneven | tenacity = Brittle | mohs = 7.5 | luster = Vitreous to adamantine; greasy when metamict. | refractive = nω = 1.925–1.961 nε = 1.980–2.015, 1.75 when metamict | opticalprop = Uniaxial (+) | birefringence = δ = 0.047–0.055 | pleochroism = Weak | streak = White | gravity = 4.6–4.7 | melt = | fusibility = close to 2,550 °C depend on Hf,Th,U,H,etc... concentrations. | diagnostic = | solubility = Insoluble | diaphaneity = Transparent to opaque | other = Fluorescent and 25px radioactive,May form pleochroic halos,Relief: high | references = }}

Zircon () is a mineral belonging to the group of nesosilicates and is a source of the metal zirconium. Its chemical name is zirconium(IV) silicate, and its corresponding chemical formula is ZrSiO4. An empirical formula showing some of the range of substitution in zircon is (Zr1–y, REEy)(SiO4)1–x(OH)4x–y. Zircon precipitates from silicate melts and has relatively high concentrations of high field strength incompatible elements. For example, hafnium is almost always present in quantities ranging from 1 to 4%. The crystal structure of zircon is tetragonal crystal system. The natural color of zircon varies between colorless, yellow-golden, red, brown, blue, and green.