Chaoite

• IMA 1968-019

Chaoit is a very rare mineral from the mineral class of elements. It crystallizes in the hexagonal crystal system and is a form of carbon. The mineral developed intergrown with graphite, 3-15 microns wide slats of black color.

Etymology and history

The mineral was discovered in 1968 by AE Goresy and G. Donnay in shockwave - fused graphite gneiss of the Ries crater in Möttingen in Bavaria. They named it after the US-China petrologists Edward Ching- Te Chao.

Classification

In the old ( 8th edition ) and new classification of minerals ( 9th Edition ) by Strunz is Chaoit in the department of " semi-metals and non-metals " sorted. The new scheme is divided here, however further. Chaoit heard now ( so far without recognition by the IMA / CNMNC ) to, graphite, diamond and silicon of the " carbon-silicon - family " together with lonsdaleite, fullerite.

Education and Locations

Chaoit formed by shock metamorphism in graphitic gneisses and meteorites. It is associated with graphite, zircon, rutile, pseudobrookite, magnetite, nickel - pyrrhotite and baddeleyite.

There are only three known localities of the mineral. In addition to the type locality was found Chaoit still in the Goalpara and Dyalpur meteorite in India.

Crystal structure

Chaoit crystallizes in the hexagonal crystal system in space group P6/mmm with the lattice parameters a = 8.95 Å and c = 14.08 Å and 168 formula units per unit cell.