77538 is a trace-element-rich breccia sample. It is a fragmental breccia with a light-coloured matrix. It has been suggested that granite clasts found in the sample owe their origin to silicate-liquid immisibility. The granite clasts contain intergrown K-feldspar and silica (see rotation 2).
The sample weighed 47.2 grams before analysis and has not been dated.
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.