Rhodochrosite, manganese carbonate, is a member of the calcite group of minerals. These are all carbonates with similar crystal structures. While calcite (calcium carbonate) is colorless or white, rhodochrosite is pink due to the presence of manganese. Rhodochrosite is a common mineral in the oxidized zones of lead deposits and in many other types of mines throughout the world. Alma, Colorado is one of many localities where excellent rhomb-shaped crystals of rhodochrosite can be found. In some localities, such as the Sweethome Mine, these crystals are large and nearly transparent, and faceted gemstones have been cut from them.