12076 is a vuggy porphyritic olivine basalt similar to 12075 (although much smaller in size). It contains olivine and pyroxene phenocrysts set in a variolitic groundmass. This is a medium-grained basic igneous rock in which pyroxenes (about 20%) and olivine (20%) phenocrysts (lengths ~3 mm) are embedded in a matrix of finer-grained, irregular intergrowths of pyroxene, plagioclase laths (20-50 microns in width and mostly untwinned) and elongated lamellae of ilmenite. Olivine crystals tend to occur in aggregates and sprays of large pyroxene grains radiating from a common point are also present. Some pyroxene phenocrysts are twinned and others have resorbed cores.
The sample weighed 54.5 grams before analysis. It has not been dated.
The mounting resin of this thin section has deteriorated over time and now contains clusters of feathery crystallites around the margins of the thin section.
Further details of this and other Apollo samples are here: http://curator.jsc.nasa.gov/lunar/
Apollo 12 returned 34 kilograms of samples, including 45 rocks, samples of lunar 'soil', and several core tubes that included material from as much as 40 centimetres below the lunar surface.
Apollo 12 rocks were almost all basalts, with only two breccias in the returned samples. The basalts at the Apollo 12 site formed 3.1 to 3.3 billion years ago, roughly 500 million years later than the Apollo 11 basalts. Overall, there is much less of the element titanium in the Apollo 12 samples than in the Apollo 11 samples, which explains the more reddish colour of this region. The differences in age and chemical composition between the Apollo 11 and Apollo 12 samples demonstrate that mare volcanism did not occur as a single, Moon-wide melting event.
Apollo 12 was launched on 14 November 1969.