Visual inspection of the dark gray rock suggested that it was probably a fine-grained basaltic igneous rock formed by the crystallization of magma near the planet’s surface.

Igneous rocks close igneous rock Igneous rocks are those which have been formed by the cooling and solidification of molten rock (magma) from underneath the earth’s crust. are formed by magma ...

Visual inspection of the dark gray rock suggested that it was probably a fine-grained basaltic igneous rock formed by the crystallization of magma near the planet's surface.