12075 (26) - Olivine basalt
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Fact sheet
Description: 

12075 is a vuggy, medium-grained olivine basalt with olivine and pyroxene phenocrysts set in a variolitic groundmass. It had also been described as an olivine dolerite cumulate. 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. Some olivine contains melt inclusions. Unusual sprays of large pyroxene grains radiating from a common point are also present.

The sample weighed 232.5 grams before analysis. It has not been dated.

Sadly, the mounting resin of this thin section has deteriorated over time and now contains clusters of feathery crystallites both around the thin section and within vesicle space (where they have an appearance not unlike some zeolite species). 

Further details of this and other Apollo samples are here: http://curator.jsc.nasa.gov/lunar/

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Not known
Ma = Millions of years ago
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igneous
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