68519 was collected as a rake sample and consists of a small lithic fragment with a glassy coating that has been partially chipped away by micrometeorite bombardment. This clast-rich impact melt has a groundmass of about 75% plagioclase feldspar with interstitial mafic minerals. Opaque minerals are small and not well developed and include armalcolite, metallic iron and troilite. Numerous inclusions of plagioclase (rotation 2) indicate that the protolith was a breccia. There is a transitional region between crystal-rich and glassy portions of the sample. The glass itself has devitrified and appears as intricate brown crystallites.
The sample weighed 10.56 grams before analysis. Problematic dating suggests the age is 3.9 billion years (Ar/Ar).
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.