mineral

Chalcedony (Common Agate pebble)

Silicon Dioxide (SiO2)

Hardness: 6.5-7 (Mohs scale); Color: translucent honey-yellow to brownish-orange; Luster: waxy to vitreous; Crystal structure: cryptocrystalline (microscopic quartz); Cleavage: none, conchoidal fracture.

Hardness: 6
Color: translucent honey-yellow to brownish-orange
Luster: waxy to vitreous

Identified April 29, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the deposition of silica from groundwater in cavities of volcanic or sedimentary rocks. This specimen is water-worn, likely from a river or beach environment.

Uses & applications

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

Geological facts

Chalcedony is a cryptocrystalline form of silica, meaning its crystals are so small they can only be seen under a microscope. It is the base mineral for agate, carnelian, and onyx.

Field identification & locations

Identify by its waxy luster, translucency when held to light, and its ability to scratch glass. Commonly found in gravel pits, riverbeds, and along shorelines.

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Mineral/Rock

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Metamorphic Rock

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mineral