gemstone
Lake Superior Agate
Silicon Dioxide (Chalcedony), SiO2
AI-generated identification · may be incorrectHardness of 6.5 to 7 on the Mohs scale, featuring distinct red, orange, and brown concentric color bands with a waxy to vitreous luster and cryptocrystalline structure.
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Physical properties
Hardness of 6.5 to 7 on the Mohs scale, featuring distinct red, orange, and brown concentric color bands with a waxy to vitreous luster and cryptocrystalline structure.
Formation & geological history
Formed roughly 1.1 billion years ago when hydrothermal solutions deposited silica into gas cavities within ancient basalt flows.
Uses & applications
Widely collected, tumbled, and cut into cabochons for jewelry and ornamental display pieces.
Geological facts
It is the official state gemstone of Minnesota and is renowned for its rich iron-oxide banding caused by glacial activity.
Field identification & locations
Identified by its waxy luster, conchoidal fracture, and striking parallel color banding; commonly found in glacial drift and gravel pits across the Upper Midwest.
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