Yogo, a Primary Deposit
Primary deposits are cave-in volcanic craters which produced vertical pipes. The pipes that brought sapphires to the surface are known as lamprophyre. Yogo® Sapphires are considered a primary deposit, because they are found in these “pipes” also known as veins, and are mined out of the hard rock.
The uniqueness of the Yogo® Sapphires is that they do not need to be heat-treated; the brilliant blue coloring is natural!
When a Yogo® sapphire is examined closely, the sapphires have sharp edges, which is typical of a primary deposit and are considered “exceptionally clean”; a significantly lower count of inclusions.
"A vertical of Rock"
The video above, by the Gemological Institute of America, features Dr. Aaron Palke and Nathan Renfor’s review of Montana Sapphires. The first 13 minutes and the last 20 minutes are dedicated to Yogo® Sapphires.
“The Yogo dyke is this vertical wall of rock that was injected into the earth that is maybe 1 to 10 meters wide.” – Dr. Aaron Palke
Mining and Exploration
The properties have a vast history of surface production, and some underground production. Roncor has an agreement to explore and evaluate the production value of the current underground mines: the American Mine, Middle Mine, English Mine and the East Mine. Additional surface exploration is also underway.
Montana Yogo® Sapphires
Non-heat treated/non-enhanced stones; unique for their cornflower blue appearance. Unlike any other sapphire!