Miller Range 03443 meteorite, Miller Range, Eastern Antarctica, Antarcticai

Regional Level Types
Miller Range 03443 meteorite	Meteorite Fall Location
Miller Range	Mountain Range
Eastern Antarctica	Region
Antarctica	Continent

Diogenite-Olivine or Diogenite, dunite
Find, 2003; 46.3 g


The small olivine-rich Miller Range 03443 meteorite has attracted considerable attention because it represents a possible dunite from the HED suite of meteorites — meteorites believed to be ultimately derived from the asteroid Vesta. The meteorite's primary constituent (> 90%) is comminuted Olivine Fa26 accompanied by minor amounts of chromite, Mg-rich orthopyroxene, troilite, and traces of Ni-poor iron and diopside. While the distribution of the various clasts and phases is heterogeneous — expected in a breccia — the olivine, orthopyroxene, and most other phases are relatively constant and unzoned as are the constituents in most diogenites. While occasional olivine fragments are found in both howardites and diogenites, the apparent absence of dunite fragments in our HED collections has been somewhat problematic. The gigantic Rheasilvia crater on Vesta suggests that deeply excavated, dunitic rocks would be expected in the midst of our now sizable collection of HED meteorites apparently derived - for the most part – from Vesta.

While the Miller Range 03443 oxygen isotope ratios are consistent with membership in the HED suite, these ratios are not in themselves dispositive. However, the referenced Beck and McSween 2010 articles and the Beck et al., (2011) article present a persuasive case that — in particular — the FeO/MnO ratios in olivines and orthopyroxenes appear to rule out alternative membership in the Mesosiderites and other groups. As olivine-rich members of the HED suite are still something of a novelty, terminology to describe olivine-rich or olivine-dominated HED meteorites is still in flux.

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References