Zircon

Zircon
Zircon crystal frae Tocantins, Brazil (2×2 cm)
General
Category	Nesosilicates
Formula (repeatin unit)	zirconium silicate (ZrSiO4)
Strunz clessification	09.AD.30
Creestal seestem	Tetragonal
Space group	Tetragonal ditetragonal dipyramidal H-M seembol: (4/m 2/m 2/m) Space group: I 41/amd
Unit cell	a = 6.607(1) Å, c = 5.982(1) Å; Z=4
Identification
Colour	Reddish broun, yellae, green, blae, gray, colourless; in thin section, colourless tae fauch broun
Creestal habit	tabular tae prismatic crystals, irregular grains, massive
Twinnin	On {101}
Cleavage	indistinct, on {110} an {111}
Fractur	Conchoidal tae uneven
Tenacity	Brickle
Mohs scale haurdness	7.5
Skinkle	Vitreous tae adamantine; glittie whan metamict.
Streak	White
Diaphaneity	Skyre tae opaque
Speceefic gravity	4.6–4.7
Optical properties	Uniaxial (+)
Refractive index	nω = 1.925–1.961 nε = 1.980–2.015, 1.75 when metamict
Birefringence	δ = 0.047–0.055
Pleochroism	Waik
Fusibility	close tae 2,550 °C depend on Hf,Th,U,H,etc... concentrations.
Solubility	Insoluble
Ither chairacteristics	Fluorescent an radioactive, mey form pleochroic halos
References

Zircon (/zɘrkon/~/zɪrkɔn/) (includin hyacinth or yellae zircon) is a mineral belangin tae the group o nesosilicates.