An electrical engineer, Thomas Allen Disselkamp works as a product development specialist for 3M. A Minnesota resident, Thomas Disselkamp is an avid agate hunter in his free time. The agate, a microcrystalline form of silica characterized by its fine grain and bright color bands, is the official state gemstone of Minnesota, and residents like Tom Disselkamp enjoy searching for the popular stone.
Lake Superior agates, which formed during volcanic eruptions around the lake approximately a billion years ago, stretch across northeastern Minnesota and attract agate hunters with their colors, luminescence, and banding. Although rock and gem shops sell beautiful agates, hunting for them is a much more exciting experience and makes for a great date or family bonding activity.
When looking for agates, hunters must develop an eye for their prominent characteristics. Agates range from translucent to opaque, but they invariably feature a waxy, almost glossy surface. The stones formed in bubble holes in molten lava and are generally round, often with pitting or dimples on the outer surfaces. Lake Superior agates are predominantly rust red because of iron, the major industrial mineral in Minnesota, but other colors like yellow and orange also exist. The famous bands are not always immediately visible. Sometimes agates show more idiosyncratic and irregular patterns not easily identified as banding.