Bidding for rare gem discovered in Colorado mine starts at $8,000

A rare gemstone discovered decades ago in a now-closed Colorado mine could sell for thousands of dollars in an October auction.

Bidding for the chunk of rhodochrosite — a rose-red gem discovered in Park County’s Sweet Home Mine in the 1990s — will start at $8,000, according to the auction website.

The mine closed in 2004 after fouryears of being unable to find new veins of the mineral.

The Colorado rhodochrosite is one of the top attractions in the Oct. 18 auction — featuring gemstones from across the globe — and has the fourth-highest starting bid of all the gems available. It falls behind only a beryl var aquamarine from Brazil, starting at $10,000; a tanzanite from Tanzania, starting at $10,500; and a quartz var citrine from Brazil, starting at $12,000.

Heritage Auctions — the auction house featuring the gemstone — is based out of Texas.

This rhodochrosite gemstone in particular was excavated from the same area of mine as the famous Wall Pocket of rhodochrosite that was reconstructed and put on display at the Denver Museum of Nature and Science, auction officials said in the listing.

“For today’s mineral collectors, the Sweet Home Mine is one of the best-known mines in the world,” Ken Kucera wrote in a Colorado School of Mines article. Kucera works in mineral collections at the university’s geology museum.

According to Kucera, the Sweet Home Mine produced some of the finest rhodochrosite in the world and has been the most important Colorado rhodochrosite producer since 1895. Now that the mine has closed, the gems are even more valuable.