72255 was collected from the side of a layered boulder from which samples 72215, 72235 and 72275 were also collected. It is a clast-rich breccia with a layered aphanitic matrix. It contains a large relic norite clast and various small clasts of silica-rich, granitic material. Granulitic polygonal anorthosite, crushed anorthosite, basaltic troctolite, ultramafic particles, and devitrified glass are also reported. It contains numerous zircons, plus troilite and metallic iron as accessory species.
The sample weighed 461.2 grams before analysis and the matrix has been dated at 3.862±0.008 billion years (Ar/Ar).
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.