NWA 8781 - a very rare ungouped carbonaceous chondrite
very nice prepared slices at good prices for such a rare class (see below)
Please send me an email to stefan@sr-meteorites.de if your favorite piece is sold already,
I have a few more pieces in different sizes in my supply.
Northwest Africa 8781 (official)
Classification: Carbonaceous chondrite (Ungrouped)
Petrography: (A. Irving and S. Kuehner, UWS, L. Garvie, ASU) Composed of very small chondrules (210±60 µm, N=20) and small mineral fragments in a black, very
fine-grained matrix (~50 vol.%). No phyllosilicates were detected by powder-XRD in the matrix. No CAI were observed. Minerals are olivine, orthopyroxene, diopside,
stained kamacite and troilite.
Geochemistry: Olivine (Fa1.1-70.7, Cr2O3 in ferroan examples = 0.21-0.40 wt.%, N = 8), orthopyroxene (Fs1.0-7.0Wo1.2-0.4, N = 3), diopside (Fs2.1Wo40.8;
Fs0.4Wo48.2). Oxygen isotopes (K. Ziegler, UNM): analyses of five 1-2 mg acid-washed non homogenized subsamples by laser fluorination gave, respectively, δ17O -
10.020, -9.832, -6.298, -5.897, -4.490; δ18O -6.085, -5.472, -1.822, -0.895, 1.221; Δ17O -6.807, -6.943, -5.336, -5.424, -5.135 (all per mil). These compositions plot on the
CCAM trend, but distinctly below the trend for CO chondrites
Classification: Carbonaceous chondrite (ungrouped). This specimen is not a CV3 chondrite (chondrule size much too small, no CAI), not a CK chondrite (no
magnetite), not a CO3 chondrite (oxygen isotopes are different, no CAI), and not a CM chondrite (matrix apparently anhydrous, oxygen isotopes displaced to more
16O-rich compositions). Therefore it seems to be an ungrouped carbonaceous chondrite.
13.354 g full slice, one side polished
SOLD
6.739 g full slice, one side polished
SOLD
3.787 g part slice, one side polished
SOLD
3.486 g part slice, one side polished
SOLD
3.006 g part slice, one side polished
SOLD
2.845 g part slice, one side polished
SOLD
1.507 g part slice, one side polished
SOLD
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