Papagoite

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Papagoite

General

Category Cyclosilicate

Formula CaCuAlSi2O6(OH)3

IMA symbol Pap[1]

Strunz classification 9.CE.05

Crystal system Monoclinic

Crystal class Prismatic (2/m)

(same H-M symbol)

Space group C2/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

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 [2][3][4][5]

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 Ca Cu Al Si2O6(O H)3.

It was discovered in 1960 in Ajo, Arizona, US, and was named after the Hia C-ed O'odham people (also known as the Sand Papago) who inhabit the area.[5] 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.[5] Its bright blue color is the mineral's most notable characteristic.

It is used as a gemstone.[6]