Microscopic diamond found in Montana

A deserted cabin sits on an 80-acre site known as the Homestead Property, located southeast of Lewistown, in central Montana, in this undated file photo. Delta Mining and Exploration Corp., plans to begin large-scale exploration in November 2004, at the Homestead site, which could be the state's first commercial diamond operation. AP photo

It was kimberlite, the molten rock in which diamonds are found, and preliminary tests had yielded a microscopic diamond with the potential for many more.

‘‘It's once in a lifetime. You just don't find things like that every day,'' said Charlton, an official with Delta Mining and Exploration Corp., a Kentucky-based firm that plans to begin large-scale

exploration of the central Montana site next month.

If more are found, the 80-acre site known as the Homestead property could become the state's first-ever commercial diamond operation and the only working diamond mine in the United States, geologists said. Canada currently has the only diamond mines operating in North America.

On the other hand, ‘‘we may not come up with anything. There's still that potential,'' Delta spokesman Alex Livak said.

Although they are rare, diamonds aren't unheard of in Montana. Prospectors have plucked the gems from stream beds and glacial valleys for years — most notably the 14-carat Lewis and Clark diamond found at the base of a steep slope near Craig in 1990.

What makes this latest discovery unique is it's believed to be the first ‘‘in-place'' diamond ever found in Montana, meaning it was created here, and not dropped in the state by a retreating glacier or other means.

‘‘There's a lot of reports of diamond occurrences,'' said David W. Baker, an earth scientist who lives about 100 miles from the site. ‘‘But a proper scientist has not before examined the locality and determined that indeed it was found in place from this locality. ... This is a very interesting site.''

Delta Mining got permission from the landowner to explore the site several years ago. But the firm is only now getting together the estimated $700,000 needed for larger soil samples and to search for more kimberlite deposits in the area, Delta chief executive Barry Rayment said.

The company said the landowner has been cooperative, but is very private. He did not return messages left at his home by The Associated Press.

Delta crews will send several hundred tons of soil to laboratories over the next few months to test for more microdiamonds or larger gemstones. An operations plan and mining feasibility study will be developed if more diamonds are found, Rayment said.

Although the odds of a major find are stacked against them, Rayment and others believe the site, and possibly others in Montana, stand a good chance of producing commercial-grade diamonds. They could be gem quality, to be sold as jewelry, or industrial quality, to make cutting tools, lenses and other products — or both.

‘‘We're two-thirds of the way there already, so the likelihood is very good,'' Charlton said. ‘‘In fact, it's one of the best (sites) I've ever seen and I've had quite a few mining properties.''

What makes the site so appealing, officials say, is its accessibility.

Normally, it takes years and mountains of dirt to find underlying kimberlite deposits, let alone diamonds. But on the ranch site southeast of Lewistown, the kimberlite is exposed, pushed to the surface by high-speed gas millions of years ago, Baker said.

That accessibility, Charlton said, should cut excavation costs and lessen any damage to the prairie and the small, vacant cabin on the site.

‘‘In doing exploration for something like this, generally the mining company has to take off hundreds of feet of overburden to get at the ore body and sample it,'' he said. ‘‘This outcrops right on top of the ground.''

Delta Mining has rights to explore five other Montana properties totaling more than 7,500 acres. The firm also owns an interest in three potential gold and diamond mines in Bolivia but is currently focusing on the Homestead property, which has the most potential, Rayment said.

Delta hopes the northern Rockies become more attractive to diamond miners as production in Canada slowly creeps south. The country's two working mines sit far to the north, but recent diamond discoveries in Alberta and Saskatchewan are pushing the industry closer to Montana, Baker said.

Montana, Wyoming and Colorado are all known to have the right kind of geology for diamonds. Northern Colorado was home to the country's only working diamond mine, Kelsey Lake, until its closure several years ago because of legal troubles, and several potential sites have also been identified in Wyoming, said Dan Hausel, a senior economic geologist for the Wyoming State Geological Survey.

‘‘There is potential (in the United States) but it's just right now all the money related to diamond exploration is being focused in Canada,'' he said. ‘‘Unfortunately, Montana hasn't been prospected as much or looked at nearly as much as Wyoming, but it's got the same type of rocks underneath it.''

Hausel expects the search for Northern Rockies diamonds to increase in coming years, but not to the point it has in Canada, which this year became the third-largest diamond producer in the world.

On the Net:

Delta Mining and Exploration: http://www.deltamine.com

Diamond basics: http://www.amnh.org/exhibitions/diamonds/

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