sedimentary
Lake Superior Agate
Silicon dioxide (SiO2)
AI-generated identification · may be incorrectHardness of 7 on the Mohs scale, waxy to vitreous luster, cryptocrystalline structure, displaying distinct concentric reddish-brown and white banding.
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Physical properties
Hardness of 7 on the Mohs scale, waxy to vitreous luster, cryptocrystalline structure, displaying distinct concentric reddish-brown and white banding.
Formation & geological history
Formed roughly 1.1 billion years ago when hydrothermal fluids filled gas cavities in basaltic lava flows.
Uses & applications
Used primarily in jewelry, cabochons, and as prized collector specimens.
Geological facts
They are the official state gemstone of Minnesota and feature characteristic iron-oxide staining from ancient glacial activity.
Field identification & locations
Easily identified by concentric color bands and waxy fracture surfaces, commonly found in glacial drift and gravel pits around the Lake Superior region.
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