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Tellurite
Tellurite
General
Category	Oxide minerals
Formula; (repeating unit)	TeO2
IMA symbol	Tlr
Strunz classification	4.DE.20
Crystal system	Orthorhombic
Crystal class	Dipyramidal (mmm) ; H-M symbol: (2/m 2/m 2/m)
Space group	Pbca
Unit cell	a = 5.6 Å, b = 12.03 Å ; c = 5.46 Å; Z = 8
Identification
Color	Yellow to white
Crystal habit	Flattened prismatic to acicular crystals, radiating groups; powdery, massive
Cleavage	Perfect on {010}
Tenacity	Flexible
Mohs scale hardness	2
Luster	Sub-adamantine
Diaphaneity	Transparent to opaque
Specific gravity	5.88 - 5.92
Optical properties	Biaxial (-)
Refractive index	nα = 2.000 nβ = 2.180 nγ = 2.350
Birefringence	δ = 0.350
Solubility	Slight in water
References

Tellurite is a rare oxide mineral composed of tellurium dioxide (Te O₂).

It occurs as prismatic to acicular transparent yellow to white orthorhombic crystals. It occurs in the oxidation zone of mineral deposits in association with native tellurium, emmonsite and other tellurium minerals. Its name comes from Tellus, which is the Latin name for the planet Earth.^[3]^[4]

It was first described in 1842 because of an occurrence in Faţa Băii, Zlatna, Alba County, Romania.^[4]