Tlalocite

Tlalocite is a rare and complex tellurate mineral with the formula Cu₁₀Zn₆(TeO₄)₂(TeO₃)(OH)₂₅Cl · 27 H₂O. It has a Mohs hardness of 1, and a cyan color. It was named after Tlaloc, the Aztec god of rain, in allusion to the high amount of water contained within the crystal structure.[1][2] It is not to be confused with quetzalcoatlite, which often looks similar in color and habit.

Tlalocite
Tlalocite spherules from Bambollita Mine (Oriental Mine), Moctezuma, Mun. de Moctezuma, Sonora, Mexico (picture width: 3 mm).
General
Category	Mineral
Formula (repeating unit)	Cu10Zn6(TeO4)2(TeO3)(OH)25Cl · 25 H2O
Strunz classification	7.DE.20
Dana classification	33.3.2.1
Crystal system	Orthorhombic Unknown space group
Unit cell	a = 16.78, b = 19.985 c = 12.069 [Å], Z = 4
Identification
Color	Capri blue, green in transmitted light
Crystal habit	Velvety crusts or spheres, arced bands
Fracture	Sectile, curved shavings or scrapings
Tenacity	Gummy and sectile
Mohs scale hardness	1
Streak	Pale blue
Diaphaneity	Translucent
Specific gravity	4.55 (measured) 4.58 (calculated)
Optical properties	Biaxial (-)
Birefringence	δ = 0.052
Pleochroism	Green, bluish green
2V angle	64
Ultraviolet fluorescence	none
Solubility	Insoluble
References

Occurrence

Tlalocite was first identified in the Bambollite mine (La Oriental), Moctezuma, Municipio de Moctezuma, Sonora, Mexico and it was approved by the IMA in 1974. It often occurs together with tenorite, azurite, malachite and tlapallite. It is found in partially oxidized portions of tellurium-bearing hydrothermal veins.[3][4]

References

1. "Tlalocite: Tlalocite mineral information and data". www.mindat.org. Retrieved 2016-09-19.
2. Barthelmy, Dave. "Tlalocite Mineral Data". www.webmineral.com. Retrieved 2016-09-19.
3. "Handbook of Mineralogy" (PDF). Retrieved 2016-09-19.
4. Williams, S.A. (1975). "Xocomecatlite, Cu₃TeO₄(OH)₄, and tlalocite, Cu₁₀Zn₆(TeO₃)(TeO₄)₂CI(OH)₂₅ . 27 H₂O, two new minerals from Moctezuma, Sonora, Mexico" (PDF). Mineralogical Magazine. 40 (311). Retrieved 2016-09-19.