Petrology of unique achondrite Queen Alexandra Range 93148: A piece of thepallasite (howardite-eucrite-diogenite?) parent body?

Queen Alexandra Range (QUE) 93148 is a small (1.1 g) olivine-rich achondrit e (mg 86) that contains variable amounts of orthopyroxene (mg 87) and kamac ite (6.7 wt% Ni), with minor augite. Olivine in QUE 93148 contains an unusu al suite of inclusions: (1) 5 x 100 mu m sized lamellae with a CaO- and Cr2 O3-rich (similar to 10 and 22 wt%, respectively) composition that may repre sent a submicrometer-scale intergrowth of chromite and pyroxene(s); (2) 75 x 500 mu m sized lamellar symplectites composed of chromite and two pyroxen es, with minor metal; (3) 15-20 mu m sized, irregularly-shaped symplectites composed of chromite and pyroxene(s); (4) 100-150 mu m sized, elliptical i nclusions composed of chromite, two pyroxenes, metal, troilite, and rare wh itlockite. Type 1, 2, and 3 inclusions probably formed by exsolution from t he host olivine during slow cooling, whereas type 4 more likely resulted fr om early entrapment of silicate and metallic melts followed by closed-syste m oxidation. Queen Alexandra Range 93148 can be distinguished from most other olivine-ri ch achondrites (ureilites, winonaites, lodranites, acapulcoites, brachinite s, Eagle-Station-type pallasites, and pyroxene pallasites), as well as from mesosiderites, by some or all of the following properties: O-isotopic comp osition, Fe-Mn-Mg relations of olivine, CaO and Cr2O3 contents of olivine, orthopyroxene compositions, molar Cr/(Cr + Al) ratios of chromite, metal co mposition, texture, and the presence of the inclusions. In terms of many of these properties, it shows an affinity to main-group pallasites. Neverthel ess, it cannot be identified as belonging to this group. Meteorite QUE 9314 8 appears to be a unique achondrite. Possibly it should be considered to be a pyroxene pallasite that is genetically related to main-group pallasites. Alternatively, it may be derived from the mantle of the pallasite (howardi te-eucrite-diogenite?) parent body.