Sample Petrographic Description
Sample Number | MIL 090073 |
Newsletter | 33,2 |
Location | Miller Range |
Field Number | 20877 |
Dimensions (cm) | 9.0 x 4.5 x 6.0 |
Weight (g) | 255.50 |
Original Classification | CO3 Chondrite |
Updated Classification | CM2 Chondrite |
Mineral Composition (%Fa & %Fs) | |
Fayalite (mol%): 26-44;Ferrosilite (mol%): 0-10 | |
Weathering | |
B/C | |
Fracturing | |
C | |
Macroscopic Description - Roger Harrington, Kathleen McBride, Cecilia Satterwhite | |
All of these carbonaceous chondrites possess dull, black fusion crust with surface areas ranging from 10 to 100%. The matrices of these meteorites are fine grained and range in color from dark gray to brown to black. Inclusions are visible in most of them and vary in color from white to gray. | |
Thin Section Description (,2) - Cari Corrigan, Linda Welzenbach | |
These meteorites are so similar that a single description suffices. The sections consist of abundant small (up to 1 mm) chondrules, chondrule fragments and mineral grains in a dark matrix. Metal and sulfide occur within and rimming the chondrules. Glass within chondrules appears to be very clear/fresh. CAIs are abundant in many sections (mostly Type A), and range in size up to 1 mm, many containing blue hibonite grains. At least one compound CAI was found. AOAs up to 1 mm exist, as well. Olivine ranges in composition from Fa0-80. Pyroxene analyses range from Fs0-44 (most from Fs0-13). These meteorites are somewhat terrestrially altered CO3 chondrites (likely type 0.0-0.2) and are probably members of the MIL 07531 pairing group. | |
Reclassification Notes (AMN 46,1) | |
Originally classified as a CO3, the sample has H, C, and N bulk and isotopic composition, as well as O isotopic composition and degree of aqueous alteration, that are consistent with CM2. Details are reported in Alexander et al. (2018) Geochim. Cosmochim. Acta 221, 406-420. |
Antarctic Meteorite Images for Sample MIL 090073 | ||||
Lab Photo(s) : | ||||
Antarctic Meteorite Images for Sample MIL 090073 | ||||
Thin Section Photo(s) : | ||||
References for Sample MIL090073 | |
Prestgard, T., Bonal, L., Eschrig, J., Gattacceca, J., Sonzogni, C., and Beck, P., 2021, Miller Range 07687 and its place within the CM-CO clan. Meteoritics & Planetary Science, 56, 1758–1783, doi: 10.1111/maps.13736. | |
Alexander, C. O. D., Greenwood, R. C., Bowden, R., Gibson, J. M., Howard, K. T., & Franchi, I. A. , 2018, A multi-technique search for the most primitive CO chondrites. Geochimica et Cosmochimica Acta, 221, 406-420, https://doi.org/10.1016/j.gca.2017.04.021. | |
McAdam, M.M., Sunshine, J.M., Howard, K.T., Alexander, C.M., McCoy, T.J., Bus, S.J., 2018, Spectral evidence for amorphous silicates in least-processed CO meteorites and their parent bodies. Icarus, 306, 32-49, https://doi.org/10.1016/j.icarus.2018.01.024. | |
Sears, D. W., 2016, The CO chondrites: Major Recent Antarctic finds, Their Thermal and Radiation History, and Describing the Metamorphic History of Members of the Class. Geochimica et Cosmochimica Acta, 188, 106–124. | |
RELAB, , Reflectance Experiment Lab , catalogue of samples. |