Stone, or rock, is a naturally occurring material composed of one or more minerals. Some common stones include: granite, marble, and slate. Laser processing of stone can be performed with a 9.3 or 10.6 micron CO₂ laser. Most stones can also be processed with a fiber laser. Laser marking of stones is achieved by creating a pattern of microfractures on the surface; this creates a light mark. Laser engraving of stone is achieved similarly to laser marking, but results in added depth. Dark, uniform stones allow for the best contrast and detail when laser marking or engraving stone.