15661 (13) Porphyritic Olivine Basalt
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Fact sheet
Description: 

15661 was collected as a rake sample. It is vesicular, vuggy and has a few olivine phenocrysts; typical of olivine-normative basalts. 15661 is a fine- to medium-grained microgabbroic mare basalt with about 60% pyroxene. Rare olivine phenocrysts reach about 1.5mm, are anhedral (see rotation 2), and contain crystallized silicate melt inclusions. Most pyroxene and olivine crystals are less than 0.5mm across. Pyroxene and olivine tend to be granular and the plagioclase feldspar forms subhedral hollow laths. A few variolitic areas are present. Chromite forms cores to some ulvospinel. Cristobalite, fayalite, ilmenite, troilite and some glass is also present. Rotation 1 shows an interstitial melt pocket.

The sample weighed 5.9 grams before analysis and has not been dated.

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

In Place
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Timescale:
Not known
Ma = Millions of years ago
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igneous
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