Colorado is a state in the western United States, the Capital is Denver, the population about 4.3 Million people. Most of the state is the prairie, a part of the Great Plains called the Colorado Eastern Plains. Its elevation ranges between 1,000 m and 2,000 m asl. To the west is the Front Range of the Rocky Mountains, with several mountains of more than 4,000 m asl. The geology is also divided into two main areas, the plains with little disturbed layers of sedimentary rocks above old cratons, the west with the typical results of an orogeny. A certain western part is called the Colorado Mineral Belt, stretching from the San Juan Mountains in the southwest to Boulder and Central City on the front range. This is where most of the historic gold and silver mining districts of Colorado are located.
There are about 700 known wild caves in Colorado. Because of the big differences in altitude, between 1,000 m and 4,000 m asl and the resulting differences in climate, the caves also have a wide range of temperatures. The caves in the lowlands have temperatures between 7 and 15 °C, others are around or below 0 °C, which often causes ice in the caves.
There are five grottos (caving clubs) in Colorado, in Denver, Boulder, LaPorte, Colorado Springs and Glenwood Springs. The largest is the 112-member Denver-based Colorado Grotto. There are two commercial caves in Colorado.
Far more interesting are the numerous show mines and mining museums of the state, so we listed 27 mining related sites.