sedimentary
Lake Superior Agate
Silicon dioxide (chalcedony), SiO2
AI-generated identification · may be incorrectHardness of 6.5 to 7 on the Mohs scale. Displays red, orange, and yellow banding with a waxy to vitreous luster and microcrystalline structure.
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Physical properties
Hardness of 6.5 to 7 on the Mohs scale. Displays red, orange, and yellow banding with a waxy to vitreous luster and microcrystalline structure.
Formation & geological history
Formed in gas cavities of ancient basaltic lava flows through the rhythmic deposition of silica-rich groundwater over one billion years ago.
Uses & applications
Widely used in jewelry, lapidary arts, and highly sought after by mineral collectors.
Geological facts
It is the official state gemstone of Minnesota and is distinguished by its characteristic iron-oxide-stained concentric color bands.
Field identification & locations
Found predominantly in glacial drift across the Upper Midwest of the United States. Identify by its distinct waxy banding and resistance to weathering.
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Sandstone or Siltstone
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Sandstone
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Shale
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Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)
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