More About Yogo Sapphires

The Treasure State - home of the Yogo Sapphire
There’s a good reason the official nickname for Montana is “The Treasure State.”  Montana is rich in gold and silver and also boasts a wide array of precious and semi-precious gemstones. The most beloved of these treasures is the Yogo Sapphire--a gemstone known for its rich blue color.  The Yogo stone exemplifies a truly rare gem.  It is an all-natural sapphire that requires no heat treatments. Ninety-five percent of the world’s sapphires must be treated with heat to achieve the brilliant colors for which sapphires are known.

Natural Yogo Sapphires, however, are never heat-treated. The true color of the Yogo Sapphires ranges from pale blue to a deep, deep hue. The world contains only one source of Yogo Sapphires, and it is in Montana, close to the little community of Utica, in the foothills of the Little Belt Mountains west of Lewistown.  We invite you to stop in at Moccasin Mountain Gallerty and see our large selection of Yogo Sapphire jewelry.

What makes the Yogo Sapphire unique?
300 million years ago, an ancient sea covered much of what is now Montana.  The seabed, under geologic pressure, formed the Madison limestone layer.  Then, 250 million years later, uplift created the Little Belt Mountains, which lie about 35 miles west and south of Lewistown.  Magma from the earth’s mantle rose into a fracture in the limestone and formed a five-mile long, ten-foot wide dike of lamproite—the Yogo Sapphire’s host rock.  Geologic surveys show this dike is 7,000 feet deep, making it the world’s largest known sapphire deposit.  Mining efforts to date have never extended deeper than 400 feet, yet Yogo Sapphires are the most precious gemstones ever to be mined in the U.S.

Although well-cut Yogos larger than one carat are rare, exceptional gems have been known to sell for up to $100,000.  The Yogo dike has produced more than $25,000,000 of the world’s most beautiful sapphires; but Yogos are embedded in hard rock, which makes mining them difficult and expensive.  Nearby, the Sapphire Village subdivision allows property owners lifetime digging rights on the old mine.  For them, rock hounding is a hobby, and residents spend summers collecting buckets of old mine dirt, leaked from flumes that sat atop the hill above Yogo Gulch nearly 100 years ago.

YOGO Mine history
Human history with the Yogo dike began in 1879, when more than 1,000 prospectors flocked to Yogo City, one of the last major gold booms in Montana.  Going west from Hobson, Montana, the road follows the Judith River to Utica, a little cow town that was painted into history by Charles M. Russell.  Eleven miles farther west, by the banks of a clear mountain stream called Yogo Creek, the miners found little gold, but they did notice small translucent blue pebbles that sank to the bottom of their sluice boxes.  Interested only in gold, the men threw these stones away.  Two years later, the boom was over, and Yogo City emptied out.

Then in 1894, locals Jake Hoover and S.S. Hobson began looking for gold again.  Legend has it that the next year, Hoover lent a schoolteacher friend a bucket of gold dirt to show her class.  When she returned the dirt, she asked if she could keep the pretty little blue stones that she had found mixed into the dirt.  Old Jake never found much gold, but he started America’s greatest adventure in mining native precious gemstones when he filled a cigar box with pretty blue pebbles and sent it to jeweler Tiffany & Co. in New York for appraisal.  There, America’s most prominent gem expert at the time identified them as “…the finest precious gemstones ever found in the United States.”  Tiffany sent Hoover a check for $3,750 and a letter explaining the sapphires were of “unusual quality.”  In 1886, Hoover, Hobson, and two others bought claims on the eastern end of the dike and started digging in earnest for the sapphires. They realized, though, with no American gem-cutting facilities, rough stones were hard to market.  Hoover sold his share of the claims, paid his debts, and joined the Alaska gold rush.

In 1923, an intense storm flooded and destroyed most of the above-ground mining structures. By the latter half of the 20th century, the mine had changed hands numerous times.  Many attempted mining this perfect stone, but high operating costs, no domestic cutting facilities, and poor marketing caused them all to fail.  Then in 1984, four local hikers made a new discovery at Yogo—a side vein to the original mine.  Those men staked a total of 14 new claims, called themselves “Vortex Mining”, sunk a 265-foot shaft, and operated successfully for several years. Unsatisfied with production and profit however, the owners closed the Vortex Mine in 2004.  

The future for Yogo Sapphires looked very dim until the spring of 2008, when Mike Roberts, a second-generation hard rock gold miner from Alaska, acquired the mine and its claims. He successfully commercially mined underground in areas overlooked and not explored by previous miners. Tragically, in March of 2012, Mike died in an accident while working underground alone in his mine.  Underground mining immediately ceased and the entire operation has been closed down for the last several years.  After Mike’s death, the mine went through rigorous safety updates and has passed all inspections to meet MSHA standards (Mine Safety and Health Administration).  The present owner, the Yogo Mining Company, plans to continue improving the mine’s infrastructure to guarantee that it is a safe, sustainable operation.  The Yogo Mining Company will operate the mine, organize the stone cutting, and distribute Yogos.  For up-to-date information, check out the articles in national jewelers publications, such as JCKNational Jeweler, and Instore Magazine.


--YOGO THE GREAT AMERICAN SAPPHIRE by Stephen M. Voynick, 1985
by Lee A. Woodward and Jerry D. Hanley, 2013                                                                  --published article by THE GEM GALLERY, Bozeman, Montana