gemstone
Lake Superior Agate
Silicon Dioxide (Chalcedony), SiO2
AI-generated identification · may be incorrectHardness of 7 on Mohs scale, waxy to vitreous luster, conchoidal fracture, and distinct parallel color banding. Specific gravity is approximately 2.65.
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Physical properties
Hardness of 7 on Mohs scale, waxy to vitreous luster, conchoidal fracture, and distinct parallel color banding. Specific gravity is approximately 2.65.
Formation & geological history
Formed roughly 1.1 billion years ago during the Keweenawan Rift Zone volcanism when silica-rich hydrothermal fluids filled gas cavities in basalt.
Uses & applications
Widely utilized in jewelry making, ornamental carvings, and as highly prized specimens for rock collectors.
Geological facts
They are the official state gemstone of Minnesota and display rich red, orange, and yellow hues caused by iron oxidation.
Field identification & locations
Identify by characteristic concentric banding and waxy luster in glacial drift, gravel pits, and eroded riverbeds around the Lake Superior region.
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