72155 is a micro-porphyritic ilmenite basalt with both olivine and abundant ilmenite phenocrysts set in holocrystalline groundmass. The average grain size is about 0.5 mm with a few ilmenite blades up to 1 mm. There is very little plagioclase present (~15%). Rotation 1 shows a compositionally zoned olivine crystal. In places, plagioclase feldspar and pyroxene are intergrown in 'bow ties' (rotation 2).
The sample weighed 238.5 grams before analysis and has not been dated.
Further details of this and other Apollo samples are here: http://curator.jsc.nasa.gov/lunar/
Apollo 17, the final manned landing mission, had two objectives: to obtain samples of ancient rocks from the lunar highlands and to look for evidence of younger volcanic activity on the valley floor.
This small Collection contains material deriving from both periods, including igneous rocks around 4.3 billion years old from the lunar highlands as well as younger volcanic samples dating from about 3.6 billion years ago.
Apollo 17 was launched on 7 December 1972.