Lake Superior Agate

Lake Superior agate is a type of iron-colored agate originating from the Lake Superior region of the United States and Canada. It commonly occurs as a collectible beach stone on the Lake Superior shoreline in Minnesota, Michigan, Wisconsin, and Ontario, and it can also be found in glacial deposits in these and several Midwestern states. As a gemstone, Lake Superior agate is valued for its vibrant bands in predominant shades of red, orange, and white, but they may also be other colors. Lake Superior agates are believed to be the world's oldest agates, having formed within the basaltic lava flows of the Midcontinent Rift System roughly 1.1 billion years ago. In 1969, the Lake Superior agate was designated by the Minnesota Legislature as the official state gemstone.