The martian meteorite ALH84001 leapt into the spotlight in late 1996 when a NASA-led research team suggested that it contained evidence of biotic activity on ancient Mars. ALH84001 is unique among the martian meteorites- a cumulate rock made up predominantly of orthopyroxene, with interstitial maskelynite (feldspar turned into a diaplectic glass by shock), apatite, chromite and sulfides. Highly brecciated fracture zones cut through the rock, presumably a result of impacts, and within these zones is a variable amount of secondary carbonate. This carbonate, the most extensive secondary mineral found in any martian meteorite, formed during significant interaction between martian crust and volatiles, and represents a unique access point toward understanding the environment of ancient Mars. However, the conditions under which this carbonate formed are less clear. While claims for evidence of biotic activity are predicated on carbonate formation at low (<100°C) temperatures under water-rich conditions, other research suggests much less hospitable conditions, with little water present and formation temperatures approaching 700°C.