Ajoite

The mineral Ajoit is a very rarely occurring sheet silicate with the chemical composition (K, Na) Cu7Al [ Si9O24 (OH ) 6] • 3H2O. It crystallizes in the triclinic crystal system and is usually arranged to find fibrous, lamellar or prismatic crystals to about half a millimeter in length of blue-green color with light green stroke color in the form of tufted. As inclusions ( inclusions) in quartz it is this also a greenish to bluish color.

Etymology and history

Was first discovered in the blue-green copper-aluminum silicate by Harry Berman ( Harvard University) in August 1941 together with dark blue Shattuckit in the "New Cornelia Mine ( Ajo Mine) " in the Little Ajo Mountains in Pima County (Arizona, USA). Berman tried together with Waldemar Theodore Schaller to determine the new mineral and describe, but died suddenly in 1944. Schaller finished the analyzes along with Angelina C. Vlisidis and named the mineral after it first locality (type locality) Ajoit.

Classification

In the now outdated but still in use 8th edition of the mineral classification by Strunz the Ajoit belonged to the mineral class of " silicates and Germanates " and then to the Department of " unclassified silicates ".

The 9th edition used since 2001 and valid by the International Mineralogical Association (IMA ) of the Strunz'schen Mineral classification assigns the Ajoit also in the class of " silicates and Germanates " there, however, in the department of " layer silicates ( phyllosilicates ) " a. This department is also further divided according to the crystal structure, so that the mineral is found in accordance with its construction in the subsection " Using simple tetrahedron meshes with 4, 5, (6) and 8 rings involved " where it is the only member of the unnamed group 9 forms. EA.70.

The classification of minerals according to Dana assigns the Ajoit in the class of " silicates and Germanates " and there in the department of " unclassified silicates ". Here he is the only member of the unnamed group 78.05.01 within the sub-division of " unclassified silicates: Possible phyllosilicates " to find.

Education and Locations

Ajoit forms as a secondary mineral in copper deposits. There he finds mostly associated or grown in quartz with Shattuckit, but may also occur depending on the locality with other accompanying minerals such as, but Konichalcit, the Bi - and Ca - containing, greenish yellow Mottramite - variety Duhamelit, muscovite, Papagoite, pyrite and sillenite.

Apart from its type locality Ajo Mountains, the mineral was still in the co- located in Pima County "Potter - Cramer Mine" ( Vulture Mountains ) and in the "Moon Anchor Mine" (Big Horn Mountains ).

In Germany Ajoit has so far been found only in Ramsbeck in the Sauerland. The only Austrian locality is the cleaning chamber Alp in the Verwallgruppe in Vorarlberg.

Other localities are the " Ashio Mine" at Ashio in Japanese Tochigi Prefecture, Khorixas in Namibia, the " Messina Mine" at Messina (now Musina ) in South Africa and Tavistock (Devon) in England (United Kingdom).

Crystal structure

Ajoit crystallized in the triclinic space group or ( Raumgruppen-Nr. 1 or 2) with the lattice parameters a = 13.64 Å; b = 14.51 Å; c = 13.62 Å; α = 107.2 °; β = 105.4 ° and γ = 110.6 ° and 3 formula units per unit cell.