73235 (83) Aphanitic Impact Melt Breccia
We would like to thank the following for the use of this sample:
73235 has a fine-grained aphanitic matrix and is trace-element-enriched, with a bulk composition similar to that of 73215 and 73217. It has a dense, aphanitic melt groundmass with seriate clast distribution. The groundmass consists mainly of plagioclase, pyroxene, opaque minerals and rare pink pleonaste spinel. Zircon is also reported in a unique clast from this sample (in section 82). Lithic clasts include granoblastic feldspathic impactities with a variety of grain sizes, shocked anorthosites, and cataclasized troctolites and norites. Many lithic clasts are strung out as schlieren within the dense matrix. Rotation 1 shows what is thought to be a recrystallised plagioclase clast. Rotation 2 focuses on a region of clast-laiden melt.
The sample weighed 878.3 grams before analysis and has been dated at 3.96 ± 0.04 billion years (Ar/Ar).
Further details of this and other Apollo samples are here: http://curator.jsc.nasa.gov/lunar/
Ma = Millions of years ago
Rock forming mineral:
- metallic iron,