Papagoite

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Papagoite
Papagoite-k-152b.jpg
Crystalline papagoite from Namibia (size: 5.9 x 3.3 x 2.1 cm)
General
Category Cyclosilicate
Formula
(repeating unit)
CaCuAlSi2O6(OH)3
Strunz classification 09.CE.05
Crystal symmetry Monoclinic 2/m
Unit cell a = 12.92 Å, b = 11.49 Å, c = 4.69 Å; β = 100.81°; Z = 4
Identification
Color Dark blue crystals, light blue when massive
Crystal habit Massive; cryptocrystalline, forming flat elongated crystals
Crystal system Monoclinic-prismatic
Cleavage Imperfect in one direction
Fracture Brittle
Mohs scale hardness 5-5.5
Luster Vitreous to dull
Streak Light blue
Specific gravity 3.25
Optical properties Biaxial (-)
Refractive index nα = 1.607 nβ = 1.641 nγ = 1.672
Birefringence δ = 0.065
Pleochroism Trichroic
2V angle Measured: 78°
References [1][2][3]

Papagoite is a rare cyclosilicate mineral. Chemically, it is a calcium copper aluminium silicate hydroxide, found as a secondary mineral on slip surfaces and in altered granodiorite veins, either in massive form or as microscopic crystals that may form spherical aggregates. Its chemical formula is CaCuAlSi2O6(OH)3.

It was discovered in 1960 in Ajo, Arizona, USA, and was named after the Sand Papago peoples (now named Hia C-ed O'odham) that inhabit the area.[3] This location is the only papagoite source within the United States, while worldwide it is also found in South Africa and Namibia. It is associated with aurichalcite, shattuckite, ajoite and baryte in Arizona, and with quartz, native copper and ajoite in South Africa.[3] Its bright blue color is the mineral's most notable characteristic.

References[edit]


Papagoite with conichalcite, from Ajo, Arizona.
Papagoite and native copper inclusions on a quartz crystal from Limpopo Province, South Africa (size 7.0 x 3.7 x 2.6 cm)