gemstone
Lake Superior Agate
Silicon dioxide (Quartz), SiO2
AI-generated identification · may be incorrectMohs hardness of 7, vitreous to waxy luster, microcrystalline quartz structure, and distinct concentric color banding in red, brown, and yellow.
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Physical properties
Mohs hardness of 7, vitreous to waxy luster, microcrystalline quartz structure, and distinct concentric color banding in red, brown, and yellow.
Formation & geological history
Formed roughly 1.1 billion years ago when hydrothermal fluids deposited silica in gas cavities of basaltic lava flows.
Uses & applications
Prized by collectors and lapidaries for cutting, polishing, and crafting into unique jewelry.
Geological facts
They are the official state gemstone of Minnesota and were widely transported by glacial activity.
Field identification & locations
Identified in the field by waxy luster, conchoidal fracture, and characteristic iron-oxide-stained concentric bands; found mostly in glacial gravels and river beds around the Lake Superior region.
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