NORTHWEST AFRICA 5206


LL3.05
standby for nwa 5206 photo
Purchased October 2007
no coordinates recorded

A single weathered (W3) meteorite weighing 1,276 g was found in Algeria and sold to a meteorite dealer in Erfoud, Morocco. Analysis and classification of the stone was conducted at Northern Arizona University (T. Bunch and J. Wittke), and it was determined that NWA 5206 is a very weakly shocked (S2), terrestrially weathered (W3), highly unequilibrated LL3.05 (or possibly lower) chondrite.

Chondrules of both type-I and type-II compositions are present in a ratio of 3:1, respectively, and chondrule textures span a broad range; porphyritic types predominate, while the remainder comprises granular, radial, cryptocrystalline, barred, and a number of unique types, some with thick mantles. In addition to the primitive compositional heterogeneity of this chondrite, other petrographic and chemical characteristics, such as the alkali-poor glassy chondrule mesostasis and the Cr distribution in ferroan olivine, has led investigators to conclude that NWA 5206 is highly unequilibrated with a subtype <3.1. More discriminating analytical techniques will be employed in future studies to verify the subtype. A more extensive review of the most recent techniques used to discriminate between the lowest petrologic types can be found on the NWA 1756 page. A comprehensive pictorial review of NWA 5206 can be found on the Meteorites Australia page showing examples of the many chondrule types and exotic components such as metallic chondrules armored with troilite, xenolithic chondrule fields, and dark inclusions.

Very few ordinary chondrites have been classified as petrologic subtype 3.05 or lower, and NWA 5206 is the only LL chondrite designated as such. The specimen of NWA 5206 shown above is a 7.47 g partial slice. The photo below shows a view of the main mass, courtesy of M. Cimala.

standby for nwa 5206 photo
Photo courtesy of Marcin Cimala—Polish Meteorite Laboratory