Tlapallite

Tlapallite

Tlapallite on matrix from Bambollita mine (La Oriental), Moctezuma, Municipio de Moctezuma, Sonora, Mexico. Picture width: 29 mm
General
Category Tellurate minerals
Formula
(repeating unit)
H6(Ca,Pb)2(Cu,Zn)3(TeO3)4(TeO6)(SO4)
Strunz classification 4.JL.25
Dana classification 34.8.2.1
Crystal system Monoclinic
Unknown space group
Unit cell a = 11.97 Å , b = 9.11 Å
c = 15.66 Å; Z = 4
Identification
Color Green
Crystal habit Thin crusts or botryoidal aggregates
Cleavage None
Mohs scale hardness 3
Luster Vitreous, Waxy
Streak Pale green
Diaphaneity Translucent
Specific gravity

5.38 (measured)

5.05-5.465 (calculated)
Optical properties Biaxial (-)
Refractive index nα = 1.815 - 1.915 nβ = 1.960 - 2.115 nγ = 1.960 - 2.115
Birefringence δ = 0.1450-0.2000
Pleochroism Moderate, different shades of green
2V angle 0
Ultraviolet fluorescence None
Fusibility Fuses readily
Diagnostic features Thin green paint-like crusts
Solubility

Soluble in cold HCl

Slightly soluble in HNO3 unless heated
References

Tlapallite is a rare and complex tellurate mineral with the formula H6(Ca,Pb)2(Cu,Zn)3(TeO3)4(TeO6)(SO4). It has a Moh's hardness of 3 and it is green in colour. It was named after the Nahua word "Tlalpalli", which translates to paint, referring to the paint-like habit of the mineral.[1] It has no uses beyond being a collector's item.

Occurrence

It was discovered in 1972 the Bambollita mine (La Oriental), Moctezuma, Municipio de Moctezuma, Sonora, Mexico, a mine known for its tellurium deposits, and it was approved by the IMA in 1977. Here, it is found as thin paint-like crusts on rock fractures and next to thin veins running through rhyolite. It is often found as a thin film on quartz, sericite, calcite or baryte, but it also forms botryoidal aggregates. It is often found alone, but may be associated with other minerals, especially carlfriesite.[2] It has also been found in the emerald mine in Tombstone District, Cochise County, Arizona in the United States.[1][3][4]

The habit of the mineral suggests it precipitates from rapidly drying acid solutions. It seems to form in the transitory phase when other tellurium minerals, like tlalocite, cesbronite, xocomecatlite, quetzalcoatlite, teineite and carlfriesite, start to break down.[2]

See also

References

  1. 1 2 "Tlapallite: Tlapallite mineral information and data.". www.mindat.org. Retrieved 2016-09-15.
  2. 1 2 S.A. Williams and Marjorie Duggan (June 1978). "Tlapallite, a new mineral from Moctezuma, Sonora, Mexico" (PDF). Mineralogical Magazine. 42: 183–186.
  3. Barthelmy, Dave. "Tlapallite Mineral Data". www.webmineral.com. Retrieved 2016-09-15.
  4. "Handbook of Mineralogy" (PDF).


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