73218 (26) Impact Melt Breccia
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Fact sheet
Description: 

73218 is a coherent impact melt rock similar to 73216 and 73275 from the same location. The fine-grained matrix has needles of plagioclase feldspar that formed from a melt and confirms this is an impact melt rock. However, before it was a melt it was a breccia, because there are relict small clasts of anorthosite and anorthositic breccia. Rotation 1 shows a remarkable pyroxene clast consisting of a larger pigeonite crystal mantled by augite. Both display fine exsolution and the latter is also twinned. Rotation 2 shows two plagioclase feldspar-rich clasts. Metallic iron, ilmenite and troilite can be seen in reflected light.

The sample weighed 39.7 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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metamorphic
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