Minerals identify

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Aenigmatite

Inosilicates

Aenigmatite, also known as Cossyrite after Cossyra, the ancient name of Pantelleria , titanium. The chemical formula is Na2Fe2+5TiSi6O20 and its structure consists of single tetrahedral chains with a repeat unit of four and complex side branches. It forms brown to black triclinic lamellar crystals. It has Mohs hardness of 3.74 to 3.85. Aenigmatite forms a solid-solution series with wilkinsonite, Na2Fe2+4Fe3+2Si6O20.

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

It was also reported from the Kaidun meteorite , possibly a Mars meteorite , which landed on March 1980 in South Yemen. Other notable studied occurrences include: * Narsaarsuk and elsewhere in Greenland. * The Khibiny alkaline massifs on Kola Peninsula. * The Yenisei Range , Russia. * The volcanic island of Pantelleria. * In the US, from Granite Mountain , near Little Rock , and Santa Rosa , Sonoma County, California . * In Australia, from Warrumbungle volcano, Nandewar volcano, and the Mount Warning complex, New South Wales; and the Peak Range Province, Queensland. * In Canada, from Mount Edziza , the Ilgachuz shield complexes. * From Logan Point quarry, Dunedin volcano, New Zealand.

Identification

Color of mineral

Black

Mohs scale ( mineral hardness )

5.5

The streak

Brown

Density ( specific gravity )

1.78
1.8
1.87

Luster ( interacts light )

Greasy
Vitreous

Crystal ( diaphaneity )

Triclinic