Granite

Granite is a tough, durable rock composed primarily of three different minerals. These minerals are easy to see due to their different colors. The white mineral grains found in granite are feldspar. It is the most abundant mineral found in granite. The light gray, glass-like grains are quartz, and the black, flake-like graines are biotite or black mica.

Travertine

Travertine is a dense, closely compacted form of limestone found mostly in banded layers. Most travertine is white or cream colored. The stone consists mainly of calcium carbonate. Travertine deposits occur specifically in areas with circulating ground water containing calcium carbonate. Travertine often forms around the mouths of hot springs. The word travertine comes from the ancient roman name for Tivoli, a town in Italy near large deposits of travertine.

Limestone

Limestone has five categories: French Coral, Texas Limestone, Hauteville, Indiana Limestone and Jeruselem Limestone. Limestone dissolves in rainwater more easily than other rocks. Rainwater picks up a small amount of carbon dioxide during its passage through the air, and that turns it into a very weak acid. Calcite is vulnerable to acid. That explains why underground caverns tend to form in limestone country, and why limestone buildings suffer from acid rainfall.