mineral

Chalcedony (specifically Agate or Water-worn Quartzite)

Silicon Dioxide (SiO2)

Hardness: 6.5–7 on the Mohs scale. Color: Translucent tan to smoky orange. Luster: Waxy to vitreous. Crystal Structure: Hexagonal (microcrystalline/cryptocrystalline). Cleavage: None (conchoidal fracture). Specific Gravity: 2.6–2.7.

Hardness: 6
Color: Translucent tan to smoky orange
Luster: Waxy to vitreous

Identified March 9, 2026More mineral →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Formed from the deposition of silica-rich water at low temperatures, typically in volcanic cavities or as replacement in sedimentary layers. These smooth specimens often originate as nodules that have been tumbled and rounded through fluvial (river) or marine action.

Uses & applications

Commonly used in lapidary work for making cabochons, beads, and ornamental carvings. Also used as a decorative stone for aquariums or garden landscaping.

Geological facts

Chalcedony has been used since the Bronze Age for seals and jewelry because it does not cling to wax. This specific rounded shape is the result of thousands of years of natural polishing by sand and water.

Field identification & locations

Identify by its translucency (light passes through the edges), waxy surface, and extreme hardness (it will scratch glass). Commonly found in riverbeds, gravel pits, and along beaches. Collectors should look for 'banding' which would further classify it as an Agate.

Other mineral specimens

See all

Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

metamorphic

Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

Green Apatite on Albite

Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]

mineral

Epidote

Epidote - Ca2(Al2,Fe3+)3(SiO4)3(OH)

mineral