Evenkite

Evenkit ( chemical name Tetracosan ) is a very rare occurring mineral from the mineral class of organic compounds and the Department of nitrogen-free hydrocarbons. It crystallizes in the monoclinic crystal system with the chemical composition ( CH3) 2 (CH2 ) 22 and developed predominantly tabular, pseudohexagonal crystals by twinning, which are either colorless or light yellow in color.

Special Features

Chemically, it is located at Evenkit to a linear aliphatic hydrocarbon or a paraffin. The average chemical composition is generally (CH3) 2 (CH2) 22 provided, which corresponds to the tetracosane. It should be noted, however, that it is merely a sum formula. In fact Evenkit is not chemically uniform structure. The chain length of the molecules can be from 20 to 31 carbon atoms. For the type material has an average chain length of 24 to 25 carbon atoms via GC -MS was determined. Aliphatic hydrocarbons with chain lengths of 25 carbon atoms have a waxy consistency, similar to the ozokerite. According Evenkit with a Mohs hardness of 1 is one of the softest minerals.

The melting point of Evenkit is, as in the analog tetracosane, at about 50 ° C. With a density of 0.87 g / ml Evenkit is one of the lightest minerals. According fragments can float on water.

Etymology and history

Evenkit was named after its type locality Evenki (now Evenki Autonomous District, Krasnoyarsk, Russia), where it was found in 1953 and first described by AV Skropyshev.

Classification

In the now outdated nomenclature of minerals according to Strunz ( 8th edition ) of the Evenkit belongs to the department of " nitrogen outdoor hydrocarbons", where it forms the paraffin series along with ozokerite and asphaltite.

The department name was not included in the new 9th edition of the Strunz'schen mineral systematics. The mineral is there only one of his group in the unnamed " subdivision 10.BA " the Department of " hydrocarbons".

In the mostly commonly used in the English-speaking classification of minerals according to Dana, the Evenkit is also the only one of his group in the Department of " salts of organic acids and hydrocarbons ."

Education and Locations

Accurate formation conditions are currently unknown, but is presumed to have secondary education.

Locations are in addition to its type locality only Curbans in France and Dubník in Slovakia.

Crystal structure

Evenkit crystallizes in the monoclinic crystal system, space group P21 / a with lattice parameters a = 7.52 Å; b = 4.98 Å; c = 32.50 Å and β ~ 90 ° and two formula units per unit cell.