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Montana Yogo Sapphire

The Yogo Dike:
Was Formed Millions of years ago. In central
Montana's. Little Belt Mountains.

Rocks in the earth's mantle, deep beneath the crust,
melted to form molten magmas. Some of those magmas
contained materials foreign to the continental crust.

One of these magmas rose into the Madison Limestone deposit, where it slowly cooled to
form a dike an average of eight feet in width, but over five miles long. As the magma in the dike crystallized, atoms of oxygen combined with atoms of aluminum to form corundum, the mineral form of aluminum oxide. the corundum formed tiny, perfectly shaped transparent crystals rather than the usual blue gray prisms.

Virtually every crystal contained traces of iron and titanium that gave each crystal a beautiful cornflower blue color. Which makes Yogo Sapphire the most precious gemstone mined in the United States.

Montana Sapphire:
is one of the state's gemstones. Indoctrinated in 1969 along with Montana Moss agate. Sapphire's fame began a century earlier in the 1860's. Unpopular at the time because the small multicolored pebbles clogged gold sluices. In a time when, Gold, was the treasure of the day.

Eventualy the US Geological Survey termed the location "America's most important gem location." The British controlled the mines for nearly 30 years, explaining why the beautiful "Cornflower Blue" Yogo's are found in the Royal Crown Jewel Collection in London.

Over the years the Yogo mines have produced an estimated 40 million dollars in the precious blue gems. The original Yogo mines are currently being worked by commercial companies. The largest cut Yogo is 10.2 carats and is in the Smithsonian Institution in Washington, DC

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