NWA R-Type (Unclassified)

R chondrite breccia, rumurutiite (tentative classification)
(possibly paired with NWA 4814) standby for northwest africa r chondrite photo
click on photo for a magnified view Found before 2007
no coordinates recorded Many possibly paired stones and fragments representing a unique rumurutiite are thought to be distributed in both Europe (300 g stone) and the United States (400 g fragments). The specimen shown above is reportedly from a lot of two large, fresh, partially fusion-crusted stones weighing together 2,635 g, acquired by American collectors/dealers. A type sample from one or more of these stones was sent to Northern Arizona University for analysis, assignment of a provisional NWA-series number, and classification; however, the exact provenance for the specimen shown above has been lost. As photographed, the specimen above exhibiting pronounced dark and lighter lithologies bears a strong resemblance to both the 300 g R3–6 NWA 2943 found in 2005, and to the 1,120 g R4 [R3–6] chondrite NWA 4814 found in 2006, either of which might or might not share a common source meteorite. A search for more information on these meteorites could help determine whether they derive from a common meteorite, or perhaps are launch paired.

This rumurutiite exhibits clasts representing a wide variety of petrologic types. Dark, highly unequiliberated clasts containing distinct chondrules represent type 3 material, while lighter clasts are more highly metamorphosed and represent petrologic types possibly as high as 6. A modified version of the Van Schmus–Wood classification scheme has been proposed by Berlin and Stöffler (2004) to accommodate the R chondrite metamorphic variation present in the pyroxene, feldspar, and sulfides, especially the lack of low-Ca pyroxene in types 5 and 6:

Modified Van Schmus–Wood Classification Scheme For R Chondrites
3 4 5 6
of olivine
>5% mean deviation homogenous homogenous homogenous
Pyroxene predominantly
low-Ca pyroxene
low-Ca and
Ca-rich pyroxene
only Ca-rich
only Ca-rich
Feldspar small glassy
isolated intergrowths networks forming well-developed
Sulfides even distribution even distribution even distribution mobilized

A more comprehensive look at the rumurutiite chondrite group can be found on the DaG 013 page. The photo shown above is a 1.89 g slice exhibiting a range of petrologic types in this R chondrite breccia.

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