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Bates Nunataks A78004
Basic information Name: Bates Nunataks A78004
     This is an OFFICIAL meteorite name.
Abbreviation: BTNA78004
This meteorite may also be called Bates Nunataks 78004 (BTN 78004) in publications.

Observed fall: No
Year found: 1978
Country: Antarctica [Collected jointly by ANSMET (US) and NIPR (Japan)]
Mass:help 1079 g
Classification
  history:
Antarctic Meteorite Newsletter:  AMN 3(1)  (1980)  LL6
AMN 4(1)  (1981)  LL6 brecciated
Meteoritical Bulletin:  MB 76  (1994)  LL6-br
NHM Catalogue:  5th Edition  (2000)  LL6
NIPR Catalogue:  2000 Edition  (2000)  LL6
MetBase:  v. 7.1  (2006)  LL6
Recommended:  LL6    [explanation]

This is 1 of 2790 approved meteorites (plus 1 unapproved name) classified as LL6.   [show all]
Search for other: LL chondrites, LL chondrites (type 4-7), Ordinary chondrites, and Ordinary chondrites (type 4-7)
Writeuphelp
Writeup from AMN 3(1):
This text was reprinted from AMN 3(1) in AMN 4(1). In some cases, it may be an updated version from the original.

Sample No.: BTNA78004

Location: Bates Nunatak

Field No.: 324

Weight (gms): 1079.0

Meteorite Type: LL6 Chondrite

 

Physical Description:

One surface of this sample is a fracture surface. The remaining surfaces of the sample are covered with thin (0.5 mm), dull black fusion crust. Regmaglypts are present on the N and S surfaces. Macroscopically, the sample appears to be composed of angular, light colored clasts, surrounded by greenish-brown to gray interstitial material. The clasts comprise approximately 70% of the surface area and have a wide range in size; some are as much as 2.0 cm in diameter. Chondrules are apparent on the surfaces exposed during cleaving. Dimensions: 12 x 7 x 7 cm.

 

Petrographic Description: Brian Mason

The section shows a granular aggregate consisting mainly of olivine and pyroxene (average grain size 0.1-0.2 mm), with minor amounts of plagioclase, nickel-iron, and troilite, and accessory chromite. Chondritic structure is barely visible in a few places, and the chondrules are somewhat fragmented. Many of the silicate grains show undulose extinction. The meteorite has a brecciated structure, and the breccia fragments are outlined by an anastomosing network of black glassy veinlets which contain numerous minute troilite globules. A small amount of limonite staining is present around some of the nickel-iron grains. Microprobe analyses show olivine (Fa30) and orthopyroxene (Fs24) of essentially uniform composition; plagioclase is somewhat variable in composition, An13-An22, average An19s. The black glass is quite variable in composition, as follows (range and average, in weight percent): SiO2 31.5-49.9, 40.4; Al2O3 0-6.3, 2.8; FeO 17.5-40.9 23.9; MgO 16.7-31.3, 27.3; CaO 0-3.3, 1.6; Na2O 0-2.4, 1.1; TiO2 0-0.15, 0.09; MnO 0.3-0.5, 0.4. The meteorite is classed as an LL6 chondrite; it shows to a high degree the brecciation characteristic of many LL chondrites.

Data from:
  MB76
  Table 2
  Line 1415:
Mass (g):1079
Class:LL6-br
Weathering grade:B
Fayalite (mol%):30
Ferrosilite (mol%):24
Catalogs:
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References: Published in Antarctic Meteorite Newsletter 3(1) (1980), JSC, Houston
Published in Meteoritical Bulletin, no. 76, Meteoritics 29, 100-143 (1994)
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Geography:

Antarctica
Coordinates:
     Catalogue of Meteorites:   (80° 15'S, 153° 30'E)
     Recommended::   (80° 15'S, 153° 30'E)

Statistics:
     This is 1 of 40129 approved meteorites from Antarctica (plus 4494 unapproved names)
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