Black Basalt with Holes

Basalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey. The most common uses for this rock are as aggregate in highway construction, railroad ballast, tile, and is commonly seen as fa?ade material, wall cladding, and flooring.