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Afghanite



Afghanite, (Na,Ca,K)8(Si,Al)12O24(SO4,Cl,CO3)3·H2O, is a hydrous sodium, calcium, potassium, sulfate, chloride, carbonate alumno-silicate mineral. Afghanite is a feldspathoid of the cancrinite group and typically occurs with sodalite group minerals. It forms blue to colorless, typically massive crystals in the hexagonal crystal system. It has a Mohs hardness of 5.5 to 6 and a specific gravity of 2.55 to 2.65. It has refractive index values of nω=1.523 and nε=1.529. It has one direction of perfect cleavage and exhibits conchoidal fracture. It fluoresces a bright orange.

Additional recommended knowledge

It was discovered in 1968 in the Lapis-lazuli Mine, Sar-e-Sang, Badakhshan Province, Afghanistan and takes its name from that country. It has also been described from localities in Germany, Italy, the Pamir Mountains, Tajikistan, near Lake Baikal in Siberia, New York and Newfoundland. It occurs as veinlets in lazurite crystals in the Afghan location and in altered limestone xenoliths within pumice in Pitigliano, Tuscany, Italy.

References

  • Mineral Data Publishing 2001
  • Mindat with location data
  • Webmineral data


 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Afghanite". A list of authors is available in Wikipedia.
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