15659 was collected together with other fragments (15633 and 15672) in a rake sample. They are grouped together because they are medium-grained vesicular samples of the abundant olivine normative Apollo 15 basalt clan. Ilmenite, chromite, ulvospinel, Ba-K feldspar, metallic iron, troilite, fayalite and silica are present as minor minerals (often found in residual patches). Rotation 1 shows a small olivine crystal fully enclosed in pyroxene. Rotation 2 shows a plagioclase-rich region of the sample.
The sample weighed 12.6 grams before analysis and has been dated at 3.34±0.04 billion years (Ar/Ar).
Further details of this and other Apollo samples are here: http://curator.jsc.nasa.gov/lunar/
There is only one thin section of this sample and sadly it has been broken.
The Apollo 15 landing site was in the Apennine Highlands, and close to Hadley Rille — a long, narrow winding valley. Approximately 76 kg of lunar material, including soil, rock, core-tube and deep-core samples, were returned to Earth.
This mission was the first flight of the Lunar Roving Vehicle which allowed the astronauts to venture further from the Lunar Module than in previous missions. During three periods of extravehicular activity, or EVA, on July 31st, and August 1st and 2nd, Scott and Irwin completed a record 18 hours, 37 minutes of exploration, travelling 17.5 miles, in the first car that humans had ever driven on the Moon.
Apollo 15 was launched on 26 July 1971.