23. Carbonate Minerals in the Ivuna Meteorite
The carbonate mineral globules in ALH 84001 are unusual, but are not unique in the universe. This view, about 0.3 millimeters across, shows similar layering of carbonate and iron oxide minerals in the carbonaceous chondrite meteorite Ivuna. The white (clear) material is magnesite (magnesium carbonate) and the black material is the iron oxide mineral magnetite (labeled “Mt”). Carbonaceous chondrite meteorites are from the asteroid belt and almost certainly never had life in them. They do contain many types of organic chemicals, but the organic chemicals do not have the characteristic chemical signatures of life as we know it. So, by themselves, the layered carbonate globules in ALH 84001 are not proof of life on Mars.
A. Bischoff (Westfälische Wilhelms-Universitat, Munich)