Basalt is a dark, hard, fine-grained, volcanic igneous rock rich in iron and poor in silica. It starts as liquid magma below ground and then flows as lava above ground. Gas pockets trapped in the lava often expand and produce surface pores. When shot in the air, lava bombs cool more quickly, producing glassier, rounder rocks.
The Basalt Desert of northern Jordan is dotted with basaltic rocks (see Lava Flow).