Sample No.: PCA91003

Location: Pecora Escarpment

Field Number: 6220

Dimensions (cm): 5.0 x 2.1 x 1.8

Weight (g): 117.2

Meteorite Type: Heat-altered coarse octahedrite?

Macroscopic Description: Roy S. Clarke,. Jr,

This somewhat elongated, irregular shaped mass has a reddish brown weathering crust that contains small patchy black areas and is mildly corrosion pitted.

Polished Section Description: Roy S. Clarke, Jr,

A slice was removed from near the heavy end of the specimen and a polished section of ~2.4 cm3 was prepared from half of it. Exterior edges of the section are covered with patches of secondary corrosion products from 50 to 350 gm thick over about 80% of the surface. Corrosion has invaded along major grain boundaries visible on sawn surfaces and on the polished section. This grain boundary pattern suggests a coarse octahedrite structure. The interior of the section, however, reveals a preterrestrial heat-altered structure, predominantly recrystallized kamacite. Dimensions of recrystallized grains vary from a few microns to a few hundreds of microns. Micron to submicron precipitates are common along kamacite grain boundaries and within kamacite grains. Many of these seem to be kamacite, but some are undoubtedly taenite. Individual kamacite grains vary in Ni and Co contents, some Ni values as low as 3.5% were observed. Typically kamacite contains ~0.15% P. Remnants of cracked and corroded schreibersite crystals are present. Much of the edge of the section has a several hundred micron rim of an α2 atmospheric ablation zone superimposed on the original heat altered structure. This specimen is possibly a preterrestrially heat-altered coarse octahedrite.