gemstone
Lake Superior Agate
Silicon dioxide (Quartz variety, SiO2)
AI-generated identification · may be incorrectHardness of 7 on the Mohs scale, red-orange and brown banding colors, waxy to vitreous luster, cryptocrystalline quartz structure.
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Physical properties
Hardness of 7 on the Mohs scale, red-orange and brown banding colors, waxy to vitreous luster, cryptocrystalline quartz structure.
Formation & geological history
Formed roughly 1.1 billion years ago via hydrothermal precipitation of silica within gas cavities of basaltic lava flows.
Uses & applications
Prized by lapidaries and collectors for cutting into cabochons, polishing, and crafting into unique jewelry.
Geological facts
Glacial activity distributed these stones across Minnesota and Wisconsin, making the Lake Superior region their primary hunting ground.
Field identification & locations
Identify by distinct parallel iron-oxide color banding, smooth tumbled texture, and conchoidal fracture. Found primarily in glacial drift, gravel pits, and lake shores.
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