A Billion Years of History (Minnesota's State Gemstone)


Agates were formed over 1 billion years ago. Molten rock called magma came up spurting from splits in the earth's surface. This magma piled up in some areas as high as 6 miles in the sky. Inside of these flows, gas bubbles were trapped in magma as it cooled and then hardened. Ground water then carried a rich solution of dissolved silica and several other minerals and entered into these vesicles and crystallized until they were completely filled.

Later during the Great Ice Age (Quaternary Period) four major glaciations occurred, The Wisconsin, The Kansan, The Illinoian and The Nebraskan. The Wisconsin Glaciation also known as the Superior Lobe moved south over these old lava flows and washed away and then redeposited our Lake Superior Agates along it's way. Eventually, the glaciers melted and left behind a wonderful trail of Lake Superior Agates. Deposits of these rare semi-precious gemstones are found in Minnesota, Michigan, Wisconsin, and Iowa.