Sample No.: PAT91501

Location: Patuxent Range

Field Number: 4742, 5482, 5772, 6254, 6261

Dimensions (cm): 19.1 x 14.3 x 14.5 plus many large fragments

Weight (g): 8550.6

Meteorite Type: L7 chondrite

Macroscopic Description: Robbie Marlow and Roberta Score

The exterior of this handsome green rock is extremely polished but no fusion crust remains on any of the many fragments collected. A minute amount of evaporite deposit lines some of the thin exterior fractures. Large (>1 cm) inclusions of copper-colored sulfides are scattered throughout this meteorite. One area shows a highly vesicular texture on both interior and exterior surfaces.

A 2 mm thick weathering rind was noted when PAT91501 was cleaved. The interior is coarse-grained, has a granular texture, and is very green in color.

The oxygen isotopic composition of PAT 91501,19 has been measured by T.K. Mayeda and R.N. Clayton, and is closest to that of L-chondrites. For PAT 91501, δ¹⁸O = +4.7‰, δ¹⁷O = +3.7‰, compared with the mean for L4, L5, and L6: δ¹⁸O = +4.70 ± 0.24, δ¹⁷O = +3.52 ± 0.14 (Clayton et al., Geochim. Cosmochim. Acta 55, 2317, 1991).

Thin Section (,26 & ,28) Description: Brian Mason

The sections show an equigranular aggregate of anhedral to subhedral olivine and pyroxene (average grain size 0.4 mm), with minor plagioclase and accessory nickel-iron and troilite. Plagioclase laths are larger than olivine and pyroxene (up to 3 mm long) and poikilitically enclose these minerals. Minor weathering is indicated by a small amount of limonitic staining in 91501,28. Microprobe analyses show the following compositions: olivine, Fa24; pyroxene, Wo2-6 Fs20; plagioclase, An12. The mineral compositions are characteristic of an L-group chondrite, but the absence of chondrules and the small amount of metal and troilite indicate complete recrystallization. The meteorite is therefore tentatively classified as an L7 chondrite; it resembles the Shaw meteorite (Geochim. Cosmochim. Acta, v. 31, p. 1705, 1967).