12021 is a coarse-grained porphyritic pigeonite basalt that has been dated at 3.3 b.y. old. It has been described as a porphyritic basalt with elongate pyroxene phenocrysts up to 2 cm in length set in a variolitic groundmass of pyroxene, plagioclase and ilmenite. Groundmass includes silica phases, pyroxferroite, metallic iron, and glass. A striking feature is the presence of large anhedral pyroxene phenocrysts up to 10 mm long. No olivine was observed. The texture of 12021 is intrafasciculate - used to describe the hollow cores of elongate plagioclase and pyroxene needles in this rock.
The sample weighed 1876.2 grams before analysis.
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.