Sample Summary - ALHA77005

Allan Hills 77005 is the type specimen of lherzolitic shergottite. It is an ultramafic cumulate consisting of olivine and chromite poikilitically enclosed by orthopyroxene. It has interstitial patches made of plagioclase (maskelynite) and clinopyroxene with oxide and phosphate minerals which typically crystallize from a residual magma. ALHA77005 is more heavily shocked than the basaltic shergottites. Mafic minerals are shock-altered and shock melt veins and pockets are common. The sawn surface of ALHA77005 shows light and dark-colored patches which represent the poikilitic and interstitial areas, respectively. Chips of both light and dark patches were sampled and two homogenized powders were prepared by the Smithsonian Institution. Analyses of the light and dark lithology powders show little difference in bulk composition. These powders are still available for allocation through MWG.