15607 (6) Olivine Basalt
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Fact sheet
Description: 

15605, 15606 and 15607 are small fragments of Fe-rich mare basalt collected as >1 cm “walnuts” from the largest soil sample 15600. 15605 is coarse-grained, 15606 is medium-grained and 15607 is fine-grained. They are all examples of olivine-normative basalt with low silica content and with some olivine. The texture of 15605, 15606 and 15607 is intergranular with numerous small olivine and pyroxene grains embedded in larger plagioclase crystals. The olivines in these fragments are not phenocrysts and generally have pyroxene overgrowths. Some have chromite and metallic iron inclusions. Pyroxene is the dominant mineral and is chemically zoned. Plagioclase grains are lath-shaped and up to 2mm long. Interstitial phases include fayalite, cristobalite (see rotation 2 - two small rectangular crystals), ilmenite, spinel, troilite and K-rich glass. Chromite is chemically zoned to ulvospinel composition.

The sample weighed 14.8 grams before analysis. 15607 has been dated at 3.27±0.12 billion years (Ar/Ar).

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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