Aenigmatite

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Aenigmatite is a sodium, iron, titanium inosilicate mineral with formula: Na₂Fe²⁺₅TiSi₆O₂₀. It forms brown to black triclinic lamellar crystals. It has Mohs hardness of 5.5 to 6 and specific gravity of 3.74 to 3.85. Aenigmatite forms a solid-solution series with wilkinsonite, Na₂Fe²⁺₄Fe³⁺₂Si₆O₂₀.

Aenigmatite is primarily found in peralkaline volcanic rocks, pegmatites, and grantes as well as silica-poor intrusive rocks. It was first described in 1865 for an occurrence in the Ilimaussaq intrusive complex of west Greenland. Its name comes from the Greek word for "riddle".

It was also reported from the Kaidun meteorite, possibly a Mars meteorite, landed on March 1980 in South Yemen. Other notable studied occurrences include: Narssarssukand elsewhere in Greenland. In the Khibiny and Lovozero massifs, Kola Peninsula, Russia. From Pantelleria, Italy. In the USA, from Granite Mountain, near Little Rock, Pulaski Co., Arkansas, and Santa Rosa, Sonoma Co., California. In Australia, from Warrumbungle volcano, Nandewar volcano, and the Mt. Warning complex, New South Wales; and the Peak Range Province, Queensland. From Logan Point quarry, Dunedin volcano, New Zealand.

[edit] External links

• Mindat with location data
• Webmineral data