Английская Википедия:Afghanite

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Шаблон:Short description Шаблон:Infobox mineral Afghanite, (Na,K)22Ca10[Si24Al24O96](SO4)6Cl6,[1] is a hydrous sodium, calcium, potassium, sulfate, chloride, carbonate alumino-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 trigonal crystal system. The lowering of the symmetry from typical (for cancrinite group) hexagonal one is due to ordering of Si and Al.[1] 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.[2] It fluoresces a bright orange.

Файл:Afghanite, pyrite, calcite.jpg
Afghanite

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 of 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.[3]

It is used as a gemstone.[4] Шаблон:Clear left

See also

References

Шаблон:Reflist

Шаблон:Commons category

  1. 1,0 1,1 Ошибка цитирования Неверный тег <ref>; для сносок Ballirano et al. 1997 не указан текст
  2. Ошибка цитирования Неверный тег <ref>; для сносок Mindat не указан текст
  3. Ошибка цитирования Неверный тег <ref>; для сносок HBM не указан текст
  4. Tables of Gemstone Identification, By Roger Dedeyne, Ivo Quintens, p.112