The Denver Museum of Nature and Science holds an aquamarine specimen valued at over $1 million, as well as specimens of the state mineral, rhodochrosite. Every September the Denver Mart, at 451 E. 58th Avenue, hosts a gem and mineral show. The state history museum, History Colorado Center, opened in April 2012. It features hands-on and interactive exhibits, artifacts and programs about Colorado history. It was named in 2013 by "True West Magazine" as one of the top-ten "must see" history museums in the country. History Colorado's Byers-Evans House Museum and the Molly Brown House are nearby.