mineral

Brown Chalcedony (Agate/Jasper)

Cryptocrystalline Quartz (SiO2)

AI-generated identification · may be incorrect

Hardness: 6.5-7 Mohs; Color: Brown to reddish-brown; Luster: Waxy to vitreous; Crystal Structure: Trigonal (microscopic); Cleavage: None; Conchoidal fracture.

Hardness: 6
Color: Brown to reddish-brown
Luster: Waxy to vitreous

Identified July 19, 2026More mineral →

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Physical properties

Hardness: 6.5-7 Mohs; Color: Brown to reddish-brown; Luster: Waxy to vitreous; Crystal Structure: Trigonal (microscopic); Cleavage: None; Conchoidal fracture.

Formation & geological history

Formed by the deposition of silica from groundwater in cavities of volcanic or sedimentary rocks. This specific specimen appears to be water-worn or weathered.

Uses & applications

Used primarily for lapidary work, jewelry (beads, cabochons), and as a decorative collector's stone.

Geological facts

Chalcedony is a broad term that includes agate, jasper, and carnelian. It has been used since the Bronze Age for seals and amulets because it does not stick to hot wax.

Field identification & locations

Identify by its waxy luster, smoothness, and the way it breaks along curved (conchoidal) surfaces. Commonly found in riverbeds, gravel pits, and desert washes.