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Watson 012
Basic information Name: Watson 012
     This is an OFFICIAL meteorite name.
Abbreviation: There is no official abbreviation for this meteorite.
Observed fall: No
Year found: 2009
Country: Australia
Mass:help 103.1 g
Meteoritical Bulletin:  MB 99  (2011)  H7
Recommended:  H7    [explanation]

This is 1 of 19 approved meteorites classified as H7.   [show all]
Search for other: H chondrites, H chondrites (type 4-7), Ordinary chondrites, and Ordinary chondrites (type 4-7)
Comments: Approved 18 Jan 2011
Writeup from MB 99:

Watson 012        30°34’S, 131°30’E

South Australia, Australia

Found: 12 May 2009

Classification: Ordinary chondrite (H7)

History: The first piece was found by A. Tomkins during May 2009. A further 11 pieces were collected from the Nullarbor Plain in 2009 by A. Tomkins and A. Langendam. The following year, on 14 April 2010, another 9 pieces were found by A. Tomkins, using a metal detector. The total number of pieces is 21.

Physical characteristics: The total mass collected weighs 103.1 g, with the largest piece measuring 3.3 cm x 2.6 cm x 1.4 cm. The exterior is a dull brown with no obvious chondrules or fusion crust. The cut surface is a rusty brown with the occasional fleck of metal and no obvious chondrules. The 21 pieces were all found within ~25 m of each other (some buried), they are all broken pieces with the same externally weathered appearance, they have the same magnetic response, and they respond similarly to a metal detector as a function of size. We have noted that other weathered meteorites on the Nullarbor show a similar breakup and dispersal pattern, which widens as a function of weathering duration.

Petrography: (Kim Lai N. Bell, Monash). A fine- to coarse-grained, granular texture distinguishes this meteorite from most chondrites. Grain sizes have a heterogeneous distribution such that fine grains are associated with domains of extensively interconnected intergranular plagioclase, and coarse grains occur away from these zones. Grain size ranges from <0.1-0.7 mm, with an average of ~0.3-0.4 mm. Mineralogy is similar to an ordinary chondrite and includes olivine (45%), pyroxene (25%), plagioclase (9%), Fe-Ni metal (8%) and troilite (10%). Olivine and pyroxene dominantly display sharp extinctions, with occasional very weakly undulose extinction being observed, plus some irregular fracturing in larger grains. Plagioclase (50 μm to 1 mm) has a distinctly unusual texture, occurring in extensively interconnected interstitial domains and containing numerous spherical inclusions of olivine and pyroxene. Nine indistinct chondrules were identified in 4 separate thin sections. These chondrules include textural types, BO, PO, POP and PP, with diameters ranging from 0.5 mm to 1 mm (average ~0.8 mm). Metal and sulfides are highly oxidized with up to 90% of these minerals being replaced.

Geochemistry: EMPA (wt%) Olivine: SiO2 = 38.63, TiO2 = 0.00, Al2O3 = 0.00, FeO = 16.04, MnO = 0.49, MgO = 44.90, CaO = 0.02, Na2O = 0.02, K2O = 0.01, (Fa16.70±0.11, n = 8). Low-Ca pyroxene: SiO2 = 54.95 TiO2 = 0.18, Al2O3 = 0.41, FeO = 10.17, MnO = 0.53, MgO = 30.92, CaO = 1.87, Na2O = 0.07, K2O = 0.01, (Fs15.11±0.22, n = 4). Plagioclase: SiO2 = 65.08, TiO2 = 0.05, Al2O3 = 22.32, FeO = 0.90, MnO = 0.01, MgO = 0.03, CaO = 3.21, Na2O = 8.95, K2O = 0.95 (An16.18±2.22, n = 7). Kamacite: Ni = 6.89, Co = 0.35. Troilite: Fe = 62.68, Ni = 0.11, Cr = 0.11. Oxygen isotopes: δ17O = +3.44, δ18O = + 5.50, Δ17O = 0.58.

Classification: Ordinary chondrite (H7, S1/2, W3)

Specimens: All pieces and four thin sections held by A. Tomkins at Monash.

Data from:
  Table 0
  Line 0:
State/Prov/County:South Australia
Origin or pseudonym:Nullarbor
Date:12 May 2009
Mass (g):103.1
Shock stage:S2
Weathering grade:W3
Fayalite (mol%):16.7
Ferrosilite (mol%):15.1
Classifier:K.-L.N. Bell
Type spec mass (g):103.1
Type spec location:Monash
Main mass:Monash
Finder:A. Tomkins
Comments:Submitted by K.-L.N. Bell, A. Tomkins
Plots: O isotopes:  
   and collections
Monash: Building 28 School of Geosciences Monash University Victoria 3800 Australia, Australia (institutional address; updated 12 Dec 2012)
References: Published in Meteoritical Bulletin, No. 99, April 2012, MAPS 47, E1-E52 (2012) [published online only]
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     Recommended::   (30° 34'S, 131° 30'E)

     This is 1 of 232 approved meteorites from South Australia, Australia (plus 3 unapproved names) (plus 4 impact craters)
     This is 1 of 702 approved meteorites from Australia (plus 46 unapproved names) (plus 27 impact craters)
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