Sample Petrographic Description
|Sample Number||DOM 10344|
|Dimensions||4.5 x 3.3 x 2.8|
|Original Classification||CR2 Chondrite|
|Updated Classification||LL3.4 Chondrite|
|Mineral Composition (%Fa & %Fs)|
|Fayalite (mol%): 3-33;Ferrosilite (mol%): 3-13|
|Macroscopic Description - Kathleen McBride, Cecilia Satterwhite|
|These carbonaceous chondrites have brown/black fusion crust with oxidation haloes and rusty areas. The dark gray/black interior has abundant chondrules/inclusions of various sizes and color. Some metal is present.|
|Thin Section Description (,2) - Linda Welzenbach, Pamela Salyer, Tim McCoy|
|These sections exhibit small (100-300 microns), well-defined, metal-rich grains, and up to 2mm chondrules and a few CAIs in a dark matrix of FeO-rich phyllosilicate. Polysynthetically twinned pyroxene is abundant. Silicates are unequilibrated; olivines range from Fa2-33, and pyroxenes from Fs1-23Wo0-2. These meteorites are CR2 chondrites and are similar enough to be initially paired.|
|Reclassification Notes (AMN 37,2)|
|Petrographic studies and INAA data provided by Alan Rubin and John Wasson (UCLA) indicate that DOM 10344 is an LL3 chondrite, probably LL3.4.
DOM 10344 has higher sulfide contents than a typical CR2. It has Radial Pyroxene and cryptocrystalline chondrules, which are very rare in CRs, and it has few igneous rims, which are common in CRs. UCLA probe data show Fa10.5±7.5 (n=16) and Fs10.9±8.7 (n=6). The PMD of Fa is 55, corresponding to subtype <3.4. It has rare clear, colorless, isotropic glass, approximately the same as for type 3.4-3.5 OC. Its Cr2O3 in ferroan olivine is 0.07±0.07 wt%, corresponding to type >3.2. So, it is probably best classified as an LL3.4.
In addition, INAA data show 472 µg/g Co and 426 ng/g Ir in DOM 10344. This compares with a mean of 490 and 360 for LL chondrites (from Wasson and Kallemeyn, 1988) and 667 and 642 for CR chondrites from Kallemeyn et al. (1994). Additionally, DOM 10344 contains 129 ng/g Au which does not distinguish it from a CR, but is nonetheless consistent with LL.