Sample Summary - EETA79001

Elephant Moraine 79001 is a basalt containing two distinct basaltic lithologies denoted A and B. It was the first example of a meteorite containing a contact between two igneous rocks. It also contains numerous patches and veins of impact melt glass, most of which are in the dominant lithology A. Lithology B is a moderately coarse-grained basalt consisting of about 60% clinopyroxene and 30 % plagioclase glass with accessory oxides, phosphates and mesostasis. The groundmass of lithology A is similar to lithology B, but it also contains about 15% xenocrysts of orthopyroxene, olivine and chromite. These xenocrysts are similar to minerals in lherzolitic shergottites. These lithologies A and B are distinct in composition.

This meteorite has been extensively sawn and numerous chips and thin sections were allocated for a wide range of studies. Homogeneous powders (20g each) were prepared by the Smithsonian Institution from both lithologies A and B. Significant amounts of these powders are still available for allocation through MWG.

The glass pockets and veins in EETA79001 are particularly interesting. It was in them that the first measurements of trapped martian atmosphere were made, providing the best proof of the group's origin on Mars. The glass is shock melt produced by an impact on Mars. The glass also is often the site of small grains of druse, carbonate and sulfate salts that formed by interaction with water on Mars. In such drusy areas of EETA79001 Wright et al (1989,1996) claim to have found martian organic compounds. McDonald and Bada (1995) interpret their analyses of amino acids in a drusy sample to be derived from Antarctic melt water. This is clearly an area for further study. The druse in this meteorite is described in more detail at this site.