Sample 77545 was collected as a rake sample. It is a vesicular impact melt breccia similar in texture and composition to 77135, collected from the large boulder nearby. This sample of impact melt has large vesicles. The texture of 77545 is poikiloblastic with interlocking irregular pigeonite oikocrysts enclosing laths and tablets of plagioclase and minor olivine. Ilmenite is also poikilitic. Mineral clasts are abundant (mostly plagioclase), but lithic clasts are rare. The mineral mode of the matrix of 77545 is 53.2% plagioclase, 44% mafic and 1.6% ilmenite.
The sample weighed 29.5 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.