Sample Name: Yamato 983885

Location: JARE IV Nunataks

Dimensions (cm): 8.4 x 5.4 x 5.2

Weight (g): 289.71

Weathering: A

Fracturing: B

Meteorite Type: Lunar Anorthositic Breccia

Macroscopic description (Kaiden H.)

It is a rounded stone with some thin yellowish green fusion crust. Angular white to gray clasts (up to 3 mm in size), white crystalline plagioclases, pyroxenes and dark grains set in a dark fine-grained matrix.

Petrographic Description (Kaiden H.)

A thin section (71-1) shows a polymict breccia containing polymineralic and monomineralic clasts (up to 1.2 mm in size) set in a dark brown clastic matrix. Most of larger clasts are polymineralic, frequently composed of calcic plagioclase pyroxene and olivine, less commonly plagioclase and olivine, or plagioclase alone. Smaller clasts are dominantly mineral fragments of plagioclase, with some pyroxenes and olivines. Glass spherules, up to 0.3 mm in diameter, are also observed.

EPMA analyses show a pyroxene composition range of En14-8sFs12-55Wo2-40; a plagioclase range of An89-98; and an olivine range of Fo32-36.

The average FeO/MnO ratios of pyroxenes (64) indicates that this rock is lunar rock. The oxygen isotopic composition (analyzed by Clayton and Mayeda) of a bulk rock sample that is δ18O = +5.65, δ17O = +2.89, Δ17O = -0.05, also indicates that the meteorite is lunar origin.