12054 (78) Ilmenite basalt
We would like to thank the following for the use of this sample:
12054 is a medium-grained, equigranular, with lath-shaped plagioclase and equant to slightly elongate pyroxene intergrown, suggestive of coetectic crystallization. Elongate ilmenite and small segregations of symplectoid mesostasis are common features. 12054 has been shocked to ~250 450 kbars. Diaplectic feldspars are highly fractured. Pyroxene crystals exhibit pronounced undulatory extinction and decreased birefringence.
Note the yellowish-orange glass at the top left of the thin section. The glass contains oblong vesicles (up to 1.2 mm) and schlieren up to 0.4 mm. It is about 0.5 mm thick in most places. Dendrites occur in some of the glass. The glass coating did not form in situ but was deposited as an impact melt splash derived from a basalt similar to 12054 (not soil). 12054 has been used for numerous consortium studies; related to exposure phenomena (micrometeorites, sputtering, solar-flare tracks, ion implantation etc). In fact, this rock was used as a sort of standard for micrometeorite zap pit, cosmic-ray track studies and irradiation history because it had a known orientation, glass coating and relatively simple history.
The sample weighed 687 grams before analysis. It has not been dated.
Further details of this and other Apollo samples are here: http://curator.jsc.nasa.gov/lunar/
Ma = Millions of years ago
Rock forming mineral:
- metallic iron