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 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
ColorDark blue crystals, light blue when massive
Crystal habit Massive; cryptocrystalline, forming flat elongated crystals
Cleavage Imperfect in one direction
Fracture Brittle
Mohs scale hardness5–5.5
Luster Vitreous to dull
Streak Light blue
Specific gravity 3.25
Optical propertiesBiaxial (-)
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 Si 2 O 6(O H)3.

It was discovered in 1960 in Ajo, Arizona, United States, and was named after the Hia C-eḍ Oʼodham 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

  1. Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi: 10.1180/mgm.2021.43 . S2CID   235729616.
  2. Mineralienatlas
  3. MinDat
  4. Webmineral
  5. 1 2 3 Handbook of Mineralogy
  6. Dictionary of Gems and Gemology By Mohsen Manutchehr-Danai p. 352