sedimentary

Jasper or Agate (Chalcedony)

Silicon Dioxide (SiO2) with impurities

Hardness: 6.5-7 on Mohs scale. Color: Brown, reddish-brown, tan, and translucent white. Luster: Waxy to vitreous. Crystal structure: Cryptocrystalline (Trigonal). Cleavage: None, exhibits conchoidal fracture.

Hardness: 6
Color: Brown, reddish-brown, tan, and translucent white
Luster: Waxy to vitreous

Identified July 1, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed from the deposition of silica-rich fluids in cavities or through the replacement of organic materials. These specimens are likely water-worn pebbles from riverbeds or glacial till.

Uses & applications

Used primarily in lapidary arts, jewelry (cabochons), and as decorative tumbling stones or collectable specimens.

Geological facts

Jasper and Agate are both varieties of chalcedony; Agate is translucent, while Jasper is opaque due to higher mineral impurities like iron oxide. These stones have been used since prehistoric times for making tools and ornaments.

Field identification & locations

Identify in the field by their smoothness, waxy luster when wet, and ability to scratch glass. Commonly found in riverbeds, gravel pits, and coastal beaches in volcanic regions.

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