Quartzite is a type of sedimentary rock that is formed from the aggregation of small pieces of mineral crystal. It is a fairly common rock and can be found in many different colors, including black, light green, purple and green (also known as ‘alexandrite’). This stone is pleochroic which means it has different optical properties in different parts of the stone, so it appears to change color when viewed from different angles. The green color of the stone is caused by a microscopic crystal inside. This natural stone has a variety of uses, and is often sold for use in kitchen countertops, bathroom vanities, tabletops and floors.