sedimentary

Jasper and Quartz conglomerate (River Rock)

Silicon Dioxide (SiO2) - Chalcedony and Quartz variety

AI-generated identification · may be incorrect

Hardness: 6.5-7.0 (Mohs); Color: Tan, cream, and reddish-brown with waxy to dull luster; Crystal structure: Microcrystalline (Cryptocrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.6-2.9.

Hardness: 6
Color: Tan, cream, and reddish-brown with waxy to dull luster

Identified February 16, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed from silica-rich fluids filling cavities in volcanic or sedimentary rocks, or as water-worn pebbles in riverbeds. These materials are often millions of years old, shaped and rounded by mechanical weathering in high-energy aquatic environments.

Uses & applications

Commonly used in landscaping and construction (river rock). Higher quality specimens are used for lapidary work, decorative cabochons, or as garden accents and aquarium stones.

Geological facts

Jasper is an opaque variety of chalcedony. The name 'Jasper' is derived from the Greek 'iaspis', meaning 'spotted stone.' It has been used for seals and amulets since ancient Mesopotamian times.

Field identification & locations

Identify by its heavy weight and extreme hardness (it will scratch glass). Often has a smooth, water-worn texture with small circular pits or 'pockmarks' on the surface common to riverbed jasper. Frequently found in gravel bars and river deltas.