Peridotite is a rock type that is more representative of Earth’s mantle than of the crust. The minerals that compose it are generally high-temperature minerals that are unstable at Earth’s surface. They are quickly altered by hydrothermal solutions and weathering. Those that contain magnesium-oxide-bearing minerals can alter to form carbonates, such as magnesite or calcite, which are much more stable at Earth’s surface. Alteration of other peridotites forms serpentinite, chlorite, and talc.

Peridotite can sequester gaseous carbon dioxide into a geologically stable solid. This occurs when carbon dioxide combines with magnesium-rich olivine to form magnesite. This reaction happens at a geologically rapid rate. The magnesite is much more stable over time and serves as a carbon dioxide sink. Perhaps this characteristic of peridotite can be used by humans to intentionally sequester carbon dioxide and contribute to solving the climate change problem.