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LaPaz Icefield 04840
Basic information Name: LaPaz Icefield 04840
     This is an OFFICIAL meteorite name.
Abbreviation: LAP 04840
Observed fall: No
Year found: 2004
Country: Antarctica [Collected by US Antarctic Search for Meteorites program (ANSMET)]
Mass:help 50.4 g
Classification
  history:
Antarctic Meteorite Newsletter:  AMN 29(1)  (2006)  R
Meteoritical Bulletin:  MB 91  (2007)  R
Antarctic Meteorite Newsletter:  AMN 31(1)  (2008)  R6
Recommended:  R6    [explanation]

This is 1 of 13 approved meteorites classified as R6.   [show all]
Search for other: Rumuruti chondrites, Rumuruti chondrites (type 4-7)
Comments: Approved 21 Feb 2006
Writeuphelp
Writeup from AMN 29(1):
Sample No.: LAP 04840
Location: LaPaz Ice Field
Field No.: 17198
Dimensions (cm):   5.0x3.0x1.75
Weight (g): 50.405
Meteorite Type: R Chondrite
LAP 04840 LAP 04840


Macroscopic Description: Kathleen McBride
Rough, black fusion crust with polygonal fractures is present on the exterior surface. The interior is a fine grained crystalline matrix with black and white crystalline inclusions. The meteorite was very hard with no rusting or apparent metal.

Thin Section (,4) Description: Tim McCoy
The section is texturally heterogeneous, containing relict chondrules up to 1 mm, isolated mineral grains of 100-200 microns and microcrystalline areas reaching 1 mm with mafic silicate grain sizes of 5-10 microns. Shock effects are pervasive, particularly in plagioclase. The rock consists of FeO-rich olivine (Fa38) and orthopyroxene (Fs30Wo1). Plagioclase is An7Or3. A brown, strongly pleochroic mineral comprises ~15% of the section. Microprobe analyses suggest hornblende with approximately 48% SiO2, 3% Na2O, 6% Al2O3, 16.5% MgO, 11% FeO, 10% CaO and < 0.5% TiO2, MnO and K2O. Low totals and the strong pleochroism may be due to structurally bound OH, as no Cl was noted in EDS analyses. Opaques include troilite, pentlandite and chromite. The meteorite is an R chondrite of petrologic type 6.

Oxygen isotope analysis laser fluorination: D. Rumble
The analysis of two silicate-rich fractions yielded δ18Ο=+4.28, δ17Ο=+4.37, and δ18Ο=+4.76, δ17Ο=+5.76, similar to other R-chondrites.

Cross-Polarized LightPlane-Polarized LightCross-Polarized LightPlane-Polarized LightReflected Light
LAP 04840 - Cross-Polarized Light LAP 04840 - Plane-Polarized Light
LAP 04840 - Cross-Polarized Light LAP 04840 - Plane-Polarized Light
LAP 04840 - Reflected Light
Data from:
  MB91
  Table 4
  Line 688:
Mass (g):50.4
Class:R
Weathering grade:A/B
Fayalite (mol%):38
Ferrosilite (mol%):30
Plots: O isotopes:  
Catalogs:
Search for this meteorite in the NASA/JSC database (U.S.):   
References: Published in Antarctic Meteorite Newsletter 29(1) (2006), JSC, Houston
Published in Meteoritical Bulletin, no. 91, MAPS 42, 413-466 (2007)
Find references in NASA ADS:
Find references in Google Scholar:
Photos:
CreditPhotos
Photographs from AMN:
Photograph from unknown source A photo is in the write-up above
Geography:

Antarctica
Coordinates:Unknown.

Statistics:
     This is 1 of 39173 approved meteorites from Antarctica (plus 5051 unapproved names)

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