Sample No.: ALHA77294

Location: Allan Hills

Field No.: B78010901

Weight (gms): 1351.3

Meteorite Type H5 Chondrite

Physical Description:

Polygonally fractured, dull, brownish-black fusion crust, approximately 1 mm thick, covers all surfaces of the meteorite (~13:5 x 9.0 x 6.0 cm), with the exception of the edges, which appear to have been spalled. White material, presumably evaporates, fill the grooves of the polygonal fractures on the B surface. This surface is more severely weathered than the other surfaces as evidenced by rounded areas of oxidation staining. The matrix of the stone is whitish-gray with areas of orangish-brown oxidation stain. Chondrules and irregular inclusions (lithic fragments?), as much as 2 mm in diameter, that are both lighter and darker than the matrix are apparent throughout the sample. After sixty hours of drying in the nitrogen cabinet, a crystalline (salt?) de-posit was noted on the corner of the W, B, and S surfaces. When the stone was cut in half no weathering rind was visible. Approximately 15% of the sawed surface appears to be metallic particles.

Petrographic Description: Brian Mason

The section shows well-developed chondritic structure, with individual chondrules ranging from 0.6-1.8 mm in diameter. The chondrules are set in a granular groundmass consisting largely of olivine and orthopyroxene, with some nickel-iron and a lesser amount of troilite. A small amount of limonite staining is present around the nickel-iron grains. Microprobe analyses show olivine (Fa17) and pyroxene (Fs15) of uniform composition. The meteorite is classified as an H5 chondrite.