Quetzalcoatlite

Quetzalcoatlite is a rare tellurium oxysalt mineral with the formula Zn₆Cu₃(TeO₆)₂(OH)₆ · Ag_xPb_yCl_x+2y. It also contains large amounts of silver- and lead(II)chloride with the formula Ag_xPb_yCl_x+2y (x+y≤2).^[2] It has a Mohs hardness of 3 and it crystallizes in the trigonal system. It has a deep blue color. It was named after Quetzalcoatl, the Aztec and Toltec god of the sea, alluding to its color.^[3][4][5] It is not to be confused with tlalocite, which has a similar color and habit.

Quetzalcoatlite
Blue quetzalcoatlite on quartz from the Bambollita Mine (Oriental Mine), Moctezuma, Mun. de Moctezuma, Sonora, Mexico. Picture width 2 mm.
General
Category	Oxide mineral
Formula	Zn6Cu3(TeO6)2(OH)6·AgxPbyClx+2y
IMA symbol	Pzl[1]
Strunz classification	4.FE.45
Dana classification	34.6.3.1
Crystal system	Trigonal
Crystal class	Hexagonal scalenohedral (3m) H-M symbol: (3 2/m)
Space group	P3m1
Identification
Color	Blue, green in transmitted light
Crystal habit	needle-like hexagonal crystals, crystalline crusts, sprays
Cleavage	Fair on {1010}
Fracture	Brittle
Tenacity	Brittle
Mohs scale hardness	3
Luster	Pearly, dull
Streak	Pale blue, almost white
Diaphaneity	Transparent
Specific gravity	6.05 (measured)
Optical properties	Uniaxial (−)
Birefringence	δ = 0.062
Pleochroism	blue-green
Ultraviolet fluorescence	None
Solubility	Insoluble in water, soluble in cold HCl and cold HNO3. Decomposes in KOH when heated
References

Occurrence

Quetzalcoatlite was first identified in the Bambollita mine (La Oriental), Moctezuma, Municipio de Moctezuma, Sonora, Mexico. It was later also found in another nearby mine, the Moctezuma mine, and it has also been found in mines in Arizona, Utah and California.^[3] It occurs as a rare mineral in the oxidized zone of tellurium-bearing hydrothermal deposits and it is often associated with hessite, galena, bornite, cerussite, azurite, chlorargyrite, teineite, quartz, baryte, khinite, dugganite, and gold.^[6]