Cinder cones are composed of dark-colored igneous rocks like basalt, diabase, and peridotite found near hot spots on tectonic plates of the Earth. The olivine is created when magma begins to cool ...

Harzburgite — a variety of peridotite — is the main rock within ... As the seawater hits the minerals, the olivine and pyroxene within the periodite turn into serpentine minerals and produce ...