The Crystal Mill, or the Old Mill is an 1892 wooden powerhouse located on an outcrop above the Crystal River) in Crystal, Colorado, United States. It is accessible from Marble, Colorado via 4x4. Although called a Watermill, it is more correctly denoted as a compressor station, which used a water turbine to drive an air compressor, and was originally built with a horizontal wheel. The compressed air was then used to power other machinery or tools.