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 grains are biotite or black mica.
Granite and Marble. How are they different?
Marble is simply limestone that has been compressed and/or heated deep within the earth’s crust. Unlike granite, marble was never molten rock, but it may have been heated and squeezed enough for the limestone grains to bend and flow. Marble is also made up of only one mineral — calcite — a relatively soft mineral with a hardness of “3”. Because marble is made entirely of calcite, it is much relatively softer than granite.