Yogo Sapphire Mining

In 1895, the Yogo Sapphire deposit was accidentally discovered by a gold prospector named Jake Hoover.  While recovering gold from his sluice, Hoover found many shiny blue pebbles and eventually sent them to Dr. George Kunz of Tiffany and Co. in New York for identification.  These were confirmed to be sapphires of the highest quality.  From that time on, Hoover and his partners focused their attention on mining for sapphires, which was much more profitable than gold.  The sapphires were found to be located in a weathered dike, and this area was quickly claimed.  As news of the sapphire discovery traveled, other claims were staked along the dike area as well.

The following year brought the arrival of a group of London gem merchants, and production increased to more than 400,000 carats before 1900, with approximately a quarter of the production being gem quality.  The remaining stones found a market for industrial use as abrasives or watch bearings. The mine at the eastern end of the deposit would become known as the English mine.  Charles Gadsen arrived in 1902 and supervised the English mine until it closed in 1929.  His house still stands in the center of the mine property.

Gadsen House


Miner working the English Mine ca. 1899

World War I brought a halt to the production of Yogo Sapphires, as miners were needed to extract metals to support the war effort.  By 1921 activity returned to a pre-war level until a flood in 1923 destroyed much of the English mine infrastructure and production declined significantly.  This natural disaster, along with competition from synthetic sapphires, were devastating for sapphire mining at Yogo Gulch.

In the years since that time, several companies have worked to mine the Yogo sapphires.  None have enjoyed the production levels and success of the earlier operations.  The operation has taken many twists and turns, and is now primarily idle, with only a small number of hand miners bringing stones to the surface.  Among this group is Montana Gem.  We have been hand mining claims on the Yogo property for over 30 years as part of a group securing access through the Sapphire Village land ownership.  This is strictly a hands-on operation utilizing picks, shovels, and rocker boxes to separate the gravel from the raw earth.  The concentrated gravel is then put through a centrifugal washing jig for further concentration, utilizing the heavy specific gravity of sapphires to separate them from other lighter weight stones.  The final concentrated gravel is then hand washed in small batches and searched for sapphires. 


Randy digging ore-bearing dirt


Randy hand-screening concentrated gravel


Randy picking Yogos from screened gravel

For further information about the history of the mine, we recommend the book The Great American Sapphire by Steve Voinick, available here.