gemstone
Lake Superior Agate
SiO2 (Quartz variety)
AI-generated identification · may be incorrectHardness 7 on Mohs scale, vitreous to waxy luster, conchoidal fracture, and distinct parallel colored banding.
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Physical properties
Hardness 7 on Mohs scale, vitreous to waxy luster, conchoidal fracture, and distinct parallel colored banding.
Formation & geological history
Formed 1.1 billion years ago in gas cavities of Precambrian basaltic lava flows through hydrothermal groundwater deposition.
Uses & applications
Prized collector mineral and crafted into polished gemstones, cabochons, and jewelry.
Geological facts
It is the official state gemstone of Minnesota and was widely distributed across the upper Midwest by glacial action.
Field identification & locations
Identify by its rich red, brown, and yellow concentric bands; commonly found in glacial drift, gravel pits, and lake shores.
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