15633 (16) Coarse Olivine Basalt
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Fact sheet
Description: 

15633 was collected together with other fragments as rake samples (15641, 15643 and 15663). They are grouped together because they are relatively coarse-grained samples of the abundant olivine­ normative Apollo 15 basalt clan. Most olivine grains are less than 1 mm; the larger ones contain silicate melt inclusions. Pyroxene grains are up to 2 mm and somewhat elongate. They are chemically zoned from pigeonite to Fe-rich augite. Plagioclase grains up to 3mm, poikilitically enclose small pyroxene, otherwise intergrown with pyroxene (rotation 2). Chromite is found in pyroxene and is overgrown with ulvospinel when it is interstitial. Minor phases include cristobalite (rectangular crystal at centre of rotation 1), fayalite, ilmenite, troilite, metallic iron and Fe-rich glass.

The sample weighed 7.4 grams before analysis and has not been dated.

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 around the thin section.

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Not known
Ma = Millions of years ago
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igneous
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