Iron Meteorites

Iron meteorites are composed largely of nickel-iron metal, and most contain only minor accessory minerals. These accessory minerals often occur in rounded nodules that consist of the iron-sulfide troilite or graphite, often surrounded by the iron-phosphide schreibersite and the iron-carbide cohenite. Despite the fact that some iron meteorites contain silicate inclusions, most have fundamentally the same superficial appearance.

Presently, iron meteorites are classified under two established systems. Just a few decades ago, iron meteorites were exclusively classified according to the macroscopic structures revealed when their polished surface was etched with nitric acid. Depending on these structures, they were separated into three classes: octahedrites, hexahedrites, and ataxites. 

IIG Group

This is a brand-new group of iron meteorites, recently under publication. Formerly known as the Bellsbank grouplet, it consists of just five members: Bellsbank, La Primitiva, Tombigbee River, Twannberg, and the recently discovered Guanaco, a meteorite that was found in the Atacama Desert, Chile, in 2000. Structurally, the irons of the IIG group are hexahedrites or coarsest octahedrites. In their structural and elemental compositions they resemble the iron meteorites of group IIAB, but they contain even less nickel and unusual, abundant ribbons of the iron-phosphide schreibersite. These ribbons often cover 15% of the etched surface of a IIG iron. This suggests that the formation of the IIG irons occurred in the outer regions of the core of a differentiated asteroid, probably distinct from the IIAB parent body

Twannberg  SWITZERLAND, IRON METEORITE Place of find: Nidau district, canton Bern, Switzerland. 47°7'28"N.,7°10'44"E. Date of find: 9 May, 1984 Classification: Iron (IIG) Total weight: 15.91 kg Circumstances of find: Found in a barley field, after ploughing.
				Twannberg 00 103.65 gr A rare Switzerland historical meteorite, nearly imposible to get ! Price on request