Sample No.: ALHA77286

Location: Allan Hills

Field No.: Y78010506

Weight (gms): 245.8

Meteorite Type: H4 Chondrite

Physical Description:

The B surface and portions of the N surface are devoid of fusion crust. The remaining surfaces have remnants of a thin black fusion crust. The surfaces that are devoid of fusion crust are rough on a small scale. It appears that many ~l mm inclusions produce the roughness. Chondrules and lithic clasts are present in the sample. Only one small fracture occurs on the T surface. No unweathered material was exposed when the sample was sawed. Dimensions:  ~7.5x5.5x3.5 cm.

Petrographic Description: Brian Mason

The section shows a close-packed aggregate of chondrules, 0.2-1.8 mm in diameter, with a relatively minor amount of matrix material. A variety of chondrule types is present, the commonest being granular olivine, olivine-pyroxene, and fine-grained pyroxene. Much of the granular pyroxene in chondrules is polysynthetically twinned clinobronzite. The matrix consists of fine-grained olivine and pyroxene with minor nickel-iron and troilite; some of the troilite occurs as rims to chondrules. The matrix is infiltrated with veinlets of red-brown limonite. Microprobe analyses show olivine of essentially uniform composition (Fs12-Fs16, average Fs14 [sic]). The meteorite is classified as an H4 chondrite.