This 37-by-25 inch aquamarine rock cavity—or vug—was found by amateur rock hound, Steve Brancato, at 12,500 feet on Mount Antero in the Sawatch Range of central Colorado. He named it Diane's Pocket as a tribute to his mother. Not intact upon discovery, the vug was meticulously reconstructed by Collector’s Edge Minerals, which has a mineral cleaning and preparation facility in Golden. The matrix contains more than 100 aquamarine crystals, as well as white feldspar, black quartz, silvery mica, and red garnets.
Aquamarines form under very specific, violent geologic conditions. Thirty-five million years ago, mineral-rich magma under high pressure intruded from below into the rock layers of the Sawatch Range. As the magma cooled, it trapped cavities of mineral-saturated fluid heated to temperatures as hot as 600° C (1,112° F). Minerals, including aquamarines, crystallized out of that fluid in these pockets. Over millions of years, the mountains were uplifted and eroded, which exposed the pockets and the crystals within them.
Diane's Pocket will be unveiled at the Museum’s annual “Museum After Dark” fundraising dinner on Friday, November 10, and will go on permanent public display in the Coors Gem and Mineral Hall on Friday, November 17.
“To find a pocket that’s that big and that complete really extends our knowledge of the formation of aquamarine and the nature of the geologic structure up on Mount Antero,” said Dr. Kirk Johnson, the Museum’s chief curator and vice president of research and collections. “It’s a phenomenal thing that people can go out and find treasures like this in the Colorado mountains today. That’s what science is all about—we’re continually making new discoveries. It’s not all last year, or last century. It’s happening right now and right here in Colorado.”
The aquamarine was donated by Museum Trustee and mineral collector, Bruce Oreck, and his wife, Cody.
