The findings reported in this paper present the best chance we have seen for identifying the remains of life on Mars,” said ...

Different minerals, like aragonite (CaCO3) and calcite (CaCO3), can have the same chemical makeup ... There are three main types of rock — igneous, sedimentary and metamorphic — with varying ...

What Was Happening on Earth at This Time The Precambrian is the earliest of the geologic ages, which are marked by different layers of sedimentary rock ... as catalysts for chemical reactions ...