Note that these minerals are present in this specimen, just too small to see. Description A mafic igneous rock from the top of Bowen's Reaction Series. Typically dark colored, although weathered specimens can appear quite light, or reddish. This vesicular or cellular specimen is full of holes produced when gas expanded as the lava was extruded to the surface.
Vesicular varieties vary widely, and grade completely into scoria.
Vesicular varieties such as this one are typically terrestrial, forming either on volcanic islands or on the continents.