68415 and 68416 were chipped off the top of a 0.5 m boulder on the rim of a 5 m crater near South Ray Crater. These samples were collected adjacent to each other and have similar lithology and composition. They are highly aluminous (Al2O3 = 28%) and are most likely crystallised impact melt (despite looking like a volcanic rock). 68415 and 68416 have an igneous intersertal texture characterized by a fretwork of plagioclase laths with interstitial olivine and pyroxene and minor occurrences of opaque minerals (ilmenite & metallic iron), phosphates, residual glass and other minerals. Rotation 1 shows an unusually long (1.9 mm) lath of simple twinned plagioclase feldspar.
The sample weighed 371.2 grams before analysis and has not been dated.
Further details of this and other Apollo samples are here: http://curator.jsc.nasa.gov/lunar/
The Apollo 16 landing site was in the hilly region around Descartes crater in the lunar highlands. The landing spot was chosen to allow the astronauts to gather geologically older lunar material (Descartes Formation and the Cayley Formation) than the samples obtained in the first four landings, which were in or near lunar maria.
The mission lasted 11.1 days, with a stay on the lunar surface of 71 hours. The crew were on the lunar surface for 20.2 hours during which they traversed approximately 27 kilometers and collected approximately 96 kilograms of samples.
Apollo 16 was launched on 16 April 1972.