NWA 7402 meteorite thin section. Optical micrographs of a currently unclassified chondrite, provisional name NWA 7402. At low magnification (top), the heterogeneity of terrestrial weathering is apparent. Patches of rust-colored alteration to the rock caused by iron oxidation distinguishes regions of extensive weathering from more pristine gray-toned rock. At higher magnification (bottom), one is able to identify individual weathering veins, and can assess whether metal grains have been completely or partially oxidized.