Antarctic Meteorite Petrographic Description

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Sample Petrographic Description

Sample Number

GRO 95555

Newsletter

19,2

Location

Grosvenor Mountains

Field Number

10997

Dimensions (cm)

6.0 x 6.0 x 5.0

Weight (g)

250.60

Original Classification

Diogenite (Unique)

Mineral Composition (%Fa & %Fs)

Ferrosilite (mol%): 24

Weathering

A/B

Fracturing

A/B

Macroscopic Description - Carol Schwarz

This specimen is angular in shape and greenish in color. There are several penetrating fractures. The exterior is somewhat polished with no fusion crust. The interior is greenish brown and crystalline with coarse-grained green and dark minerals. (It is coarser than PAT91501 (L7 Chondrite) and ALHA77005 (SNC) and contains no plagioclase.)

Thin Section Description (,2) - Brian Mason, Tim McCoy

The section shows a polygonal-granular aggregate of anhedral orthopyroxene, the grains ranging from 0.3 to 2.4 mm across. Pyroxene composition is essentially uniform, Wo₂Fs₂₄. Accessory phases include SiO₂, chromite, an iron sulfide (probably troilite), and weathering products of metal and troilite. The composition is that of a diogenite, but the texture is unique; it shows no sign of the brecciation and shock deformation characteristic of other diogenites.
Aluminum-26 Activity: Dave Lindstrom
The sample was radioassayed for Al-26 because it had not fusion crust and might have been a terrestrial rock. Estimated Al-26 activity of 50±10 dpm/hg is similar to that of diogenites and other achondrites.

Antarctic Meteorite Images for Sample GRO 95555

Lab Photo(s) :

Lab Photo of Sample GRO 95555 Showing Bottom North View

Lab Photo of Sample GRO 95555 Showing Top East View

Lab Photo of Sample GRO 95555 Showing Top North View

Lab Photo of Sample GRO 95555 Showing Top South View

Lab Photo of Sample GRO 95555 Showing Top West View

Antarctic Meteorite Images for Sample GRO 95555

Thin Section Photo(s) :

Thin Section Photograph of Sample GRO 95555 in Cross-Polarized Light

Thin Section Photograph of Sample GRO 95555 in Plane-Polarized Light

Thin Section Photograph of Sample GRO 95555 in Reflected Light

References for Sample GRO95555

McCoy, T.J., 2015, Meteorite Misfits: Fuzzy Clues to Solar System Processes. In Righter, K., Corrigan, C.M., McCoy, T.J., and Harvey, R.P. Meteorites: A Pictorial Guide to the Collection, First Edition , AGU Wiley, , pp. 145-152 .

Mittlefehldt, D. W., 2015, Asteroid (4) Vesta: I. The howardite-eucrite-diogenite (HED) clan of meteorites. , Chemie der Erde - Geochemistry, 75 Issue 2 , Jun-15 , 155-183 , ISSN 0009-2819 , http://dx.doi.org/10.1016/j.chemer.2014.08.002 .

Le Corre, L., Reddy, V., Sanchez, J. A., Dunn, T., Cloutis, E. A, Izawa, M. R. M, Mann, P., Nathues, A., 2015, Exploring exogenic sources for the olivine on Asteroid (4) Vesta. , Icarus, 258 , 483-499 .

Greenwood, R. C., Barrat, J. A., Yamaguchi, A., Franchi, I. A., Scott, E. R., Bottke, W. F., Gibson, J. M., 2014, The oxygen isotope composition of diogenites: Evidence for early global melting on a single, compositionally diverse, HED parent body. , Earth and Planetary Science Letters, 390 , 165-174 .

Mittlefehldt, D. W., Beck, A. W., Lee, C.-T. A., Mcsween, H. Y., Buchanan, P. C., 2012, Compositional constraints on the genesis of diogenites. , Meteoritics & Planetary Science, 47 , 72-98 , http://dx.doi.org/10.1111/j.1945-5100.2011.01314.x .

Wang, K., Moynier, F., Dauphas, N., Barrat, J. A., Craddock, P., Sio, C. K., 2012, Iron isotope fractionation in planetary crusts. , Geochimica et Cosmochimica Acta, 89 , 15-Jul-12 , 31-45 , ISSN 0016-7037 , http://dx.doi.org/10.1016/j.gca.2012.04.050 .

Paniello, R. C., Moynier, F., Beck, P., Barrat, J. A., Podosek, F. A., Pichat, S., 2012, Zinc isotopes in HEDs: Clues to the formation of 4-Vesta, and the unique composition of Pecora Escarpment 82502. , Geochimica et Cosmochimica Acta, 86 , 1-Jun-12 , 76-87 , ISSN 0016-7037 , http://dx.doi.org/10.1016/j.gca.2012.01.045 .

Mayne, R. G., Sunshine, J. M., Mcsween Jr., H. Y., Bus, S. J., Mccoy, T. J., 2011, The origin of Vesta's crust: Insights from spectroscopy of the Vestoids. , Icarus, 214 Issue 1 , Jul-11 , 147-160 , ISSN 0019-1035 , http://dx.doi.org/10.1016/j.icarus.2011.04.013 .

Le Corre, L., Reddy, V., Nathues, A., Cloutis, E. A., 2011, How to characterize terrains on 4 Vesta using Dawn Framing Camera color bands?. , Icarus, 216 Issue 2 , Dec-11 , 376-386 , ISSN 0019-1035 , http://dx.doi.org/10.1016/j.icarus.2011.09.014 .

Schiller, M., Baker, J., Creech, J., Paton, C., Millet, M., Irving, A., Bizzarro, M., 2011, Rapid Timescales for Magma Ocean Crystallization on the Howardite-Eucrite-Diogenite Parent Body. , ApJ, 740 , L22 , http://dx.doi.org/10.1088/2041-8205/740/1/L22 .

Barrat, J. A., Yamaguchi, A., Zanda, B., Bollinger, C., Bohn, M., 2010, Relative chronology of crust formation on asteroid Vesta: Insights from the geochemistry of diogenites. , Geochimica et Cosmochimica Acta, 74 Issue 21 , 1-Nov-10 , 6218-6231 , ISSN 0016-7037 , http://dx.doi.org/10.1016/j.gca.2010.07.028 .

Scott, E. R. D., Greenwood, R. C., Franchi, I. A., Sanders, I. S., 2009, Oxygen isotopic constraints on the origin and parent bodies of eucrites, diogenites, and howardites. , Geochimica et Cosmochimica Acta, 73 Issue 19 , 1-Oct-09 , 5835-5853 , ISSN 0016-7037 , http://dx.doi.org/10.1016/j.gca.2009.06.024 .

Barrat, J. A., Yamaguchi, A., Greenwood, R. C., Benoit, M., Cotten, J., Bohn, M., Franchi, I. A., 2008, Geochemistry of diogenites: Still more diversity in their parental melts. , Meteoritics & Planetary Science, 43 , 1759-1775 , http://dx.doi.org/10.1111/j.1945-5100.2008.tb00641.x .

Klima, R. L., Pieters, C. M., Dyar, M. D., 2008, Characterization of the 1.2 µm M1 pyroxene band: Extracting cooling history from near-IR spectra of pyroxenes and pyroxene-dominated rocks. , Meteoritics & Planetary Science, 43 , 1591-1604 , http://dx.doi.org/10.1111/j.1945-5100.2008.tb00631.x .

Schultz, L., Franke, L., 2004, Helium, neon, and argon in meteorites: A data collection. , Meteoritics & Planetary Science, 39 , 1889-1890 , http://dx.doi.org/10.1111/j.1945-5100.2004.tb00083.x .

Hiroi, T., Pieters, C. M., Vilas, F., Sasaki, S., Hamabe, Y., Kurahashi, E., 2001, The mystery of 506.5 nm feature of reflectance spectra of Vesta and Vestoids: Evidence for space weathering? . , Earth Planets Space, 53 , 1071-1075 .

Papike, J. J., Shearer, C. K., Spilde, M. N., Karner, J. M., 2000, Metamorphic diogenite Grosvenor Mountains 95555: Mineral chemistry of orthopyroxene and spinel and comparisons to the diogenite suite. , Meteoritics & Planetary Science, 35 , 875-879 .

RELAB, , Reflectance Experiment Lab , catalogue of samples, .

, PLATE Preface-Pictorial Guide to Selected Meteorites, 2015, In Righter, K., Corrigan, C.M., McCoy, T.J., and Harvey, R.P. Meteorites: A Pictorial Guide to the Collection, First Edition , AGU Wiley, Book Plates, .

Antarctic Meteorite Petrographic Description

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