Sample No.: ALHA81022

Location: Allan Hills

Field No.: 1482

Weight (gms): 912.5

Meteorite Type: H4 Chondrite

Physical Description: Roberta Score

The bottom surface shows relief with many chondrules apparent. All other surfaces are covered with a thin dull black fusion crust. This stone was extremely hard to chip. The small piece that fell off revealed an evenly weathered interior with several inclusions visible. Dimensions: 11.5 x 10 x.5.5 cm.

Petrographic Description: Brian Mason

The section shows a close-packed aggregate of chondrules and chondrule fragments, up to 2.5 mm across, with interstitial fine-grained matrix. A wide variety of chondrule types is present, the commonest being porphyritic olivine, granular olivine and olivine-pyroxene, barred olivine, and fine-grained radiating pyroxene. Some intergranular glass within the chondrules is pale brown and transparent, but is usually turbid and partly devitrified. Much of the pyroxene is polysynthetically twinned clinobronzite. Small areas of brown limonite are concentrated around the margins of the section. Microprobe analyses show olivine (Fa19) and pyroxene (Fs17) of essentially uniform composition (% mean deviation FeO 2-3). The texture is similar to that of type 3 chondrites, but the homogeneous nature of the olivine and pyroxene indicates type 4; the meteorite is classified as an H4 chondrite. It closely resembles ALHA78084 (recently reclassified from H3 to H4), with which it is tentatively paired.