Sample No.: ALHA79001

Location: Allan Hills

Field No.: 1171

Weight (gms): 32.31

Meteorite Type: L3 Chondrite (tentative)

Physical Description: Roberta Score

Five exterior surfaces have a dull reddish-brown color while the sixth surface has a iridescent reddish-brown color. Though the interior is extremely weathered, clasts are visible. ALHA79001 and ALHA79003 are probably the same meteorite. Dimensions: 4 x 3.5 x 1.5

Petrographic Description: Brian Mason

The polished thin section shows a closely packed aggregate of chondrules (0.2-2 mm in diameter) and irregular crystalline aggregates, set in a small amount of dark fine-grained matrix which includes minor subequal amounts of nickel-iron and troilite. A considerable variety of chondrules is present, the most common being granular olivine with or without polysynthetically twinned clinopyroxene, porphyritic olivine, and fine-grained pyroxene. Some chondrules have intergranular transparent pale brown glass, in others the glass is turbid and partly devitrified. Some weathering is indicated by the presence of a moderate amount of brown limonite as veins and patches. Microprobe analyses show a wide range in the composition of olivine (Fa6-39) and pyroxene (Fs2-31); the pyroxene is a low-calcium clinopyroxene (CaO = 0.2-1.8%). This range of composition, together with the presence of glass and twinned clinopyroxene, indicates type 3, and the small amount of nickel-iron suggests L group; the meteorite is therefore tentatively classed as an L3 chondrite.