JIDDAT AL HARASIS 846


Chondrite, type 3.5-ungrouped
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Found March 17, 2011
19° 50' 20" N., 55° 52' 12" E.

A moderately weathered (W2) 260.1 g stone meteorite was found in the Dhofar region in Oman by Pierre-Marie Pelé and Vincent Lejeune. It was noted by Pierre-Marie Pelé that due to a typo the meteorite was mistakenly classified with a JaH name rather than a Dhofar name. A sample of the stone was provided to the University of Washington in Seattle (A. Irving and S. Kuehner) and the University of New Mexico (oxygen isotopes; K. Ziegler) for analysis and classification, and Jiddat al Harasis 846 was determined to be an ungrouped petrologic type 3 ordinary chondrite.

This highly unequilibrated (olivine Fa0.6-38.1) meteorite is similar in appearance to unequilibrated L and LL chondrites in exhibiting medium-sized chondrules (0.2–2.2 mm) in a fine-grained matrix. It is composed primarily of olivine, orthopyroxene, clinopyroxene, and sodic plagioclase, along with lesser amounts of chromite, troilite, and FeNi-metal. The occurrence in JaH 846 of some chondrules that contain major orthopyroxene + a silica polymorph (probably cristobalite) is noteworthy.

Seven subsamples of JaH 846 were utilized by K. Ziegler for an O-isotopic analysis, with the resulting plots defining a trend line distinct from those of the H, L, and LL ordinary chondrite groups and reflecting comparatively much higher δ18O values (see top diagram below). Interestingly, the O isotope plots overlap with the single O isotope plot determined by Weber and Bischoff for the ungrouped ordinary chondrite HaH 180 (see bottom diagram below). In addition, the mineralogical similarities between these two ungrouped chondrites could indicate an inherent genetic relationship.

O-Isotopic Plots For JaH 846 and Ordinary Chondrites
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Diagram credit: Ziegler et al., 78th MetSoc, #5052 (2015)

O Isotope Comparison Between JaH 846 and HaH 180
JaH 846: orange symbols; HaH 180: pink symbol
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Diagram adapted from Meteoritical Bulletins 107 (JaH 846) and 81 (HaH 180)

The O isotope values for JaH 846 plot slightly above the TFL and within a field occupied by a small number of anomalous, ungrouped, non-carbonaceous chondrites including HaH 180, NWA 960, NWA 2335, and NWA 2336. Together with the NWA-series meteorites 2040 [LL], 2041 [L], 3114 [L], 3127 [LL], 3157 [L], 4294 [LL], 4298 [LL], 4486 [L], 4531 [LL], 5717 [L+LL; photo courtesy of Paul Swartz], NWA 7835 [acho-ung; Irving et al., 2014, #5332; photo courtesy of Stefan Ralew], and NWA 10769 [acho-ung; Moggi Cecchi et al., 2016, #2696], these O-isotopic values infer a possible "supra-TFL" genetic grouping which together plot along a slope that is distinct from the ordinary chondrites. It is demonstrated in the diagram below that these meteorites plot far away from the trend lines for the H, L, and LL ordinary chondrite groups and probably represent several previously unrecognized parent asteroids (Irving et al., 2014, #5332).

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Diagram credit: Rumble III et al., 38th LPSC, #2230 (2007)

The JaH 846 specimen shown above is a 9.7 g cut section with a fusion-crusted side, while that below is an in situ photo of the JaH 846 chondrite shown courtesy of Pierre-Marie Pelé. In addition, excellent photos of a 12.87 g full slice of this meteorite can be found on his Meteor-Center webpage.

JaH 846 in situ as Discovered in the Oman Desert
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Photo courtesy of Pierre-Marie Pelé—Meteor-Center