Article: Afghanite: Sar-e-Sang, Badakhshan Province, Afghanistan.(Connoisseur's Choice)

Feldspathoids are peculiar minerals. Compositionally, most appear to be complex chemical repositories whose major purpose seems to be the accommodation of some ions that might best go elsewhere (such as into a feldspar in the case of aluminum) if there were only enough silica in the system to get things reorganized. Familiar examples include nepheline, leucite, and members of the sodalite and cancrinite groups. Most collectors are familiar with the vibrant blue of sodalite and the yellow of cancrinite; alas, both are typically in massive, generally interesting, though not particularly desirable, specimens. Recently, however, the legendary lapis lazuli (lazurite) occurrence ...

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