NWA 8037 Type 3.4 Metal-Poor Ordinary Chondrite Meteorites for Sale
Location: Northwest Africa, location unknown. Purchased in 2013.
Classification: Type 3.4 metal-poor chondrite (S2, W1/2).
Description: History: Purchased by Eric Twelker in February 2013 from a Moroccan dealer at the Tucson Gem and Mineral Show.
Petrography: (A. Irving and S. Kuehner, UWS) Relatively fresh specimen composed of very closely-packed, well-formed, medium-sized (0.4-2.1 mm) chondrules in a sparse black matrix with very low metal content. Olivine, orthopyroxene, pigeonite, diopside, sodic plagioclase, altered kamacite, taenite, troilite and rare chromite.
Geochemistry: Olivine (Fa0.5-94.8; Cr2O3 in ferroan olivine 0.09-0.22 wt.%, mean 0.12±0.05 wt.%, N = 8), orthopyroxene (Fs0.8-22.4Wo0.5-3.2), pigeonite (Fs22.9Wo10.7), diopside (Fs2.4Wo39.3). Oxygen isotopes (K. Ziegler, UNM): analyses of acid-washed subsamples by laser fluorination gave (all in per mil): δ17O = 2.700, 2.988, 2.873; δ18O = 3.800, 4.255, 4.097; Δ17O = 0.694, 0.741, 0.710 (for a TFL slope of 0.528 per mil).
Classification: Ordinary chondrite (Type 3). The low metal content and freshness of this unequilibrated chondrite specimen are at odds with its oxygen isotopic composition, which plots on the trend for H chondrites. Estimation of subtype based on histograms of Cr2O3 distribution in ferroan olivine given in Fig. 4 of Grossman and Brearley (2005).
Comment: Recent classificaitons have revealed a number of unequilbrated chondrites with low metal and istopes at odds with the olivine analysis. Querry -- could there be more than three types of "ordinary" chondrite?
|Weight: 93.2 gm|