15075 (42) Pigeonite Basalt
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Fact sheet
Description: 

15075 is a coarse-grained porphyritic pigeonite basalt with subophitic matrix. 15076 is a sister sample. Pyroxene and plagioclase compose 90% of the rock; accessories include chromite­, ulvospinel, pyroxferroite, cristobalite (best seen in rotation 1, but one crystal visible in rotation 2), tridymite, ilmenite, metallic iron and fayalite. The pyroxenes are highly zoned and up to 6 mm long. The groundmass includes complex intergrowths of fayalite + Ca-rich pyroxene + silica which may be “breakdown products” of pyroxferroite.

The sample weighed 809.3 grams before analysis and has been dated at 3.45±0.025 billion years (Ar/Ar).

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

The mounting resin of this thin section has deteriorated over time and now contains clusters of colourful dendrites (obvious in reflected light) within and around the thin section.

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Not known
Ma = Millions of years ago
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igneous
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