73255 is essentially an agglomeritic bomb with a clast-rich, non-vesicular core surrounded by a rind (up to 1 cm thick) of vesicular breccia that generally has a sharp contact with the interior core. The core is itself an agglomeration of melt breccias with numerous distinct clasts of various rock types. 73255 is a fragment-laden, impact-melt rock containing a high percentage of relict rock clasts; including clasts of gabbronorite, pyroxene anorthosite, mare basalt, felsite and aphanitic microbreccia. One gabbronorite clast contains 53% plagioclase feldspar, 40% orthopyroxene, 5% augite and ~0.5% ilmenite. Minor mineral phases include apatite, whitlockite, stanfieldite (Ca-Mg-rich phosphate), chromite, troilite, metallic iron, armalcolite and rutile. Minute grains of K-feldspar and K-Si glass are also reported.
The sample weighed 394.1 grams before analysis and has been dated at 3.88±0.04 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.