sedimentary

River Jasper (Chert/Chalcedony)

Silicon Dioxide (SiO2) with iron oxide impurities

AI-generated identification · may be incorrect

Hardness: 6.5-7 (Mohs scale); Color: Yellow-brown, tan, and black with mottled patterns; Luster: Dull to waxy; Crystal Structure: Microcrystalline; Cleavage: None/Conchoidal fracture; Specific Gravity: 2.6-2.9

Hardness: 6
Color: Yellow-brown, tan, and black with mottled patterns
Luster: Dull to waxy

Identified May 22, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the accumulation and silicification of microcrystalline quartz or organic matter in sedimentary environments. Its rounded edges suggest significant weathering and transport in a river or creek bed.

Uses & applications

Used in lapidary work for cabochons and tumbled stones, aquarium decoration, and as a durable material for pathways or landscaping.

Geological facts

Jasper has been used for thousands of years as a gemstone and for making tools due to its hardness and ability to hold a sharp edge when fractured.

Field identification & locations

Identify in the field by its hardness (will scratch glass), smooth waxy feel when wet, and lack of visible grains. Commonly found in riverbeds and gravel pits worldwide.