Sample No.: PCA91002

Location: Pecora Escarpment

Field Number: 5499

Dimensions (cm): 7.8 x 4.9 x 4.7

Weight (g): 210.2

Meteorite Type: Ungrouped chondrite (similar to ALH85151 and Carlisle Lake)

Macroscopic Description: Robbie Marlow

One third of PCA91002 is covered with dull, dark brown fusion crust. Evaporite deposit is present on the interior and exterior surfaces. The interior matrix is fine-grained, dark gray, and contains numerous inclusions which have a wide range of sizes. Sulfides are present.

Thin Section (,8) Description: Brian Mason

The section shows numerous polycrystalline silicate clasts (up to 1.2 mm in maximum dimension), some small chondrules (up to 0.5 mm across), and mineral grains in a finely-granular gray matrix. A moderate amount of sulfides is present, much of it as minute grains disseminated through the matrix. No nickel-iron was seen. The meteorite appears to be unweathered. Microprobe analyses show olivine and pyroxene of variable composition. Olivine compositions show a prominent peak at Fa39, with occasionally more magnesian grains (CV FeO is 44). The pyroxene is almost entirely low-Ca: Wo0.3-5, Fs1-28; one grain of diopside, Wo45Fs12, was analyzed. Maskelynite is present in a few clasts. The sulfides are mainly pentlandite, with minor troilite. This meteorite cannot readily be placed in any of the recognized chondrite classes, and hence is recorded as ungrouped. It is very similar to ALH85151 and Carlisle Lake (Geochim. Cosmochim. Acta, v. 53, p. 3035, 1989; v. 55, p. 2657, 1991).