Optical Microscopy of Meteoritic Metal

Home The Micrographs Field of View Techniques Contact Me

NWA3133 (Metachondrite)

Several stones totaling 4.2 kg were found in the Sahara desert.

 

NWA3133 is an unusual meteorite. It is highly equilibrated, as shown by the absence of chondrules and a triple junction silicate texture. This meteorite was initially classified as a L7 chondrite, but subsequent work revealed isotopic similarity to CV chondrites. Therefore, NWA3133 may represent extensive equilibration of a CV3 protolith.

 

Unfortunately, this meteorite is highly weathered with alteration features corresponding to a weathering grade of W3 - W4. The metal particles have been partially to completely replaced by iron hydroxides. Only a few relatively unaltered metal grains are present. This surviving metal consists of zoned taenite associated with some kamacite. In every case, zoned taenite exhibits a clear-etching rim and martensite interior. No taenite cloudy zone structure was observed.