15643 (15) Coarse Olivine Basalt
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Fact sheet
Description: 

15643 was collected together with other fragments (15633, 15641 and 15663) in a rake sample. 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 and sometimes twinned (see rotation 1 & 2). Plagioclase grains up to 3mm, poikilitically enclose small pyroxene, otherwise intergrown with pyroxene. Chromite is found in pyroxene and is overgrown with ulvospinel when it is interstitial. Minor phases include cristobalite, fayalite, ilmenite, troilite, metallic iron and Fe-rich glass.

The sample weighed 17.9 grams before analysis and has not been dated.

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

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Not known
Ma = Millions of years ago
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igneous
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