Papagoite

(repeating unit)CaCuAlSi₂O₆(OH)₃IMA symbolPap^[1]Strunz classification9.CE.05Crystal systemMonoclinicCrystal classPrismatic (2/m)
(same H-M symbol)Space groupC2/mUnit cella = 12.92 Å, b = 11.49 Å,
c = 4.69 Å; β = 100.81°; Z = 4IdentificationColorDark blue crystals, light blue when massiveCrystal habitMassive; cryptocrystalline, forming flat elongated crystalsCleavageImperfect in one directionFractureBrittleMohs scale hardness5–5.5LusterVitreous to dullStreakLight blueSpecific gravity3.25Optical propertiesBiaxial (-)Refractive indexn_α = 1.607 n_β = 1.641 n_γ = 1.672Birefringenceδ = 0.065PleochroismTrichroic2V angleMeasured: 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]

References