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Ungrouped Achondrites

Ungrouped achondrites for sale Ungrouped Achondrites Many achondrites don’t fit easily into established classification schemes, and most of them are thought to be unique, and thus rather valuable samples of their respective parent bodies. Some of these ungrouped achondrites are evolved meteorites, similar to planetary meteorites, or HED achondrites, while others are clearly primitive achondrites, similar to brachinites, acapulcoites, or lodranites. Evolved achondrites: An intriguing example of such an achondrite is NWA 011 (pairing with the NWA 2976), a small stone that was recovered from Northwest Africa in 1999. Originally, it was identified as a eucrite, but subsequent chemical and isotopic studies proved that it represents a new type of basaltic achondrite, genetically unrelated to the members of the HED group. Hence, NWA 011 is believed to represent a distinct parent body, an asteroid equally evolved and of a similar size as the HED parent body, 4 Vesta. Another example is the most unusual Ibitira, a meteorite that fell in Brazil in 1957. Ibitira was also classified as an unique eucrite – it is unbrecciated, displays an unusual vesicular texture, and shows a formation age that predates most of the known HED members. More recently, detailed oxygen isotopic studies have shown that it’s more than likely that Ibitira isn’t a eucrite at all, but a meteorite from a so far unsampled differentiated asteroid that has yet to be determined. Primitive achondrites: There are several ungrouped primitive achondrites, such as Divnoe or Zag (b), two meteorites that are closely related to the brachinite group. It has not yet been determined if these ungrouped primitive members originated on the same parent body as the brachinites and simply represent different degrees of thermal processing. Alternatively, they may have originated on one or more different parent bodies that share a similar history and composition to the brachinite parent body. Some other interesting primitive achondrites are only represented by a single find, providing inadequate justification for the establishment of a new group. For example, our own find, ITQIY from Western Sahara, is primarily composed of the Mg-rich pyroxene, enstatite, and Ni-Fe metal, the texture Itqiy is like a lodranite.

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