Iron, IIAB, recrystallized hexahedrite
(Compositionally related to group IIG)
Found before 1935
32° 30' N., 85° 30' W., approx.
A single iron mass of 94 kg was found by a farmer and brought to the Carver Museum, Tuskegee Institute, Tuskegee, Alabama in the 1930's. It was subsequently recognized by L. La Paz and given the name Carver in 1969.
Utilizing HfW chronometry and employing more precise W isotope data corrected for neutron capture effects, Mei et al. (2020) calculated the core formation age for the IIAB parent body to be ~0.6 m.y. after CAIs. Carver was originally a single hexahedrite crystal that experienced a violent shock event accompanied by relaxation heating; melting of FeS has occurred. This event was followed by recrystallization of the metal to form a structure composed of a polycrystalline assemblage of small mm-sized grains of kamacite. Similar shock-recrystallized hexahedrites can be found among our collections.
Recently, it was argued by Wasson and Choe (2009) that group IIG irons are chemically similar to those of the IIAB iron group, forming extensions to IIAB trends on elementAu diagrams. They suggest that the formation of IIG irons occurred inside isolated P-rich cavities that remained after crystallization of an evolved IIAB magma (see the Tombigbee River page for more complete details).
Five other hexahedrites have been found in the Southeast U. S., but all are chemically distinct and unpaired. The specimen of Carver shown above is an 8.3 g interior slice. The photo below shows the reassembled original slice from which this partial slice was taken.
Photo courtesy of Steve ArnoldInternational Meteorite Brokerage