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O'Malley 021
Basic information Name: O'Malley 021
     This is an OFFICIAL meteorite name.
Abbreviation: There is no official abbreviation for this meteorite.
Observed fall: No
Year found: 2012
Country: Australia
Mass:help 140.8 g
Classification
  history:
Meteoritical Bulletin:  MB 104  (2015)  H4
Recommended:  H4    [explanation]

This is 1 of 6031 approved meteorites (plus 2 unapproved names) classified as H4.   [show all]
Search for other: H chondrites, H chondrites (type 4-7), Ordinary chondrites, and Ordinary chondrites (type 4-7)
Comments: Approved 18 Jul 2015
Writeuphelp
Writeup from MB 104:

O’Malley 021        30°42’47.30"S, 131°27’35.90"E

South Australia, Australia

Purchased: 2012 May 18

Classification: Ordinary chondrite (H4)

History: Larger piece + two fragments found by A. Langendam on a claypan.

Physical characteristics: The larger sample has a series of large crack and 65% fusion crust, the smaller samples also have some fusion crust.

Petrography: (L. Bowlt, Monash) Poorly defined chondrules, ranging in size up to 2 mm occur in an oxidized recrystallised matrix. Mineralogy includes olivine, pyroxene, plagioclase, Fe-Ni metal and troilite. Chondrule mesostases are moderately fine grained and plagioclase has not formed distinct individual grains. Chondrule types include PO, RP, CC and BO. Troilite grains are small (30 microns) and diffuse, whereas there are relatively large (200 micron) metal grains. Most olivine grains show sharp extinction, although some show undulose extinction and there is no evidence of shock lamellae. Widespread oxide veins branch throughout the sample. Metal and troilite grains show similar levels of weathering, 60-70% in total.

Geochemistry: (L. Bowlt, Monash) Microprobe analyses show that olivine and pyroxene compositions are uniform: olivine Fa17.1-18.4, mean Fa17.8±0.65 , n=5; Low-Ca pyroxene Fs15.2-15.9 , mean Fs15.5±0.4 , n=3.

Classification: Ordinary chondrite (H4, S3, W3)

Specimens: All specimens and one thin-section held by A. Tomkins.

Data from:
  MB104
  Table 0
  Line 0:
State/Prov/County:South Australia
Origin or pseudonym:Nullarbor Plain
Date:P 2012 May 18
Latitude:30°42'47.30"S
Longitude:131°27'35.90"E
Mass (g):140.8
Pieces:3
Class:H4
Shock stage:S2
Weathering grade:W2
Fayalite (mol%):17.8
Ferrosilite (mol%):15.5
Wollastonite (mol%):1.40
Classifier:L. J. Bowlt, Monash
Type spec mass (g):136.9
Type spec location:Monash
Main mass:Monash
Finder:A. Langendam
Comments:Submitted by (A. Tait, A. Tomkins, A. Bowlt, S. Nutku, J. Savage)
Institutions
   and collections
Monash: Building 28 School of Geosciences Monash University Victoria 3800 Australia, Australia (institutional address; updated 12 Dec 2012)
Catalogs:
References: Published in Meteoritical Bulletin, no. 104, MAPS 52, 2284, Octover 2017, http://onlinelibrary.wiley.com/doi/10.1111/maps.12930/full
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Geography:

Australia
Coordinates:
     Recommended::   (30° 42' 47"S, 131° 27' 36"E)

Statistics:
     This is 1 of 239 approved meteorites from South Australia, Australia (plus 2 unapproved names) (plus 4 impact craters)
     This is 1 of 715 approved meteorites from Australia (plus 45 unapproved names) (plus 27 impact craters)
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