mineral

Tumbled Chalcedony Pebble

Silicon Dioxide (SiO2)

AI-generated identification · may be incorrect

Hardness 6.5-7 on Mohs scale, translucent to sub-translucent, vitreous to waxy luster, cryptocrystalline structure, shell-like (conchoidal) fracture with no cleavage, light tan to greyish color with subtle mottling.

Identified July 26, 2026More mineral →

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Physical properties

Formation & geological history

Formed through precipitation from silica-rich fluids filling cavities and veins in host rocks at low temperatures. Commonly found in sedimentary, volcanic, and metamorphic environments.

Uses & applications

Used in lapidary arts, jewelry making, tumbled stone collections, and ornamental crafts.

Geological facts

Chalcedony is a cryptocrystalline form of silica, composed of very fine intergrowths of quartz and moganite. Water-worn beach or river pebbles often achieve a natural polish like this specimen.

Field identification & locations

Identified by its waxy luster, microcrystalline texture, and toughness. Commonly found in riverbeds, lake shores, gravel pits, and coastal beaches around the world.