Basalt, a dark and fine-grained igneous rock, is formed when liquid magma from volcanoes cools to form solid rock. It has been used in architecture since the Roman era and Basalt is durable like granite with similar features to limestone. With its beautiful, neutral tones, basalt is an excellent choice for interior or exterior areas. It can even be used in exterior sidewalk applications. One of the densest stones you’ll find, basalt is also recommended for fireplaces, tub surrounds and showers, vanities and more.