sedimentary

Jasper Quarzite (possibly Lake Superior Agate mix)

Silicon Dioxide with Iron Oxide inclusions (SiO2 + Fe2O3)

Hardness: 6.5-7 (Mohs scale), Color: Reddish-brown, tan, and creamy white bands, Luster: Vitreous to waxy, Crystal Structure: Hexagonal (Microcrystalline), Cleavage: None (conchoidal fracture), Specific Gravity: 2.6-2.7

Hardness: 6

Identified March 29, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the precipitation of silica from groundwater in the cavities of volcanic rocks or within sedimentary layers. This specimen likely originates from the Lake Superior region, dating back approximately 1.1 billion years to the Keweenawan Rift.

Uses & applications

Used primarily for lapidary work (tumbling and polishing), jewelry making, and as a popular decorative collection item for rockhounds.

Geological facts

Iron impurities are what provide the distinctive red and brown 'rust' colors. The Lake Superior Agate is the official state gem of Minnesota and is highly prized for its unique banding patterns.

Field identification & locations

Identify in the field by looking for 'potato-skin' texture on the exterior, waxy luster when wet, and the presence of red/orange banding. Commonly found on beaches, in gravel pits, and along riverbeds in the Upper Midwest United States.

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