mineral

Chalcedony (specifically Agate or Carnelian variety)

Cryptocrystalline Silica (SiO2)

Hardness: 6.5-7 on Mohs scale; Color: brownish-orange (carnelian-like), translucent; Luster: waxy to vitreous; Crystal structure: Trigonal/Monoclinic (microscopic); Cleavage: none, conchoidal fracture.

Hardness: 6
Color: brownish-orange (carnelian-like), translucent
Luster: waxy to vitreous

Identified March 13, 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 via the precipitation of silica from groundwater in cavities of igneous rocks or sedimentary formations. Most specimens range from a few million to hundreds of millions of years old.

Uses & applications

Used extensively in jewelry (cabochons, beads), micro-precision bearings, mortar and pestles, and as a popular collector's mineral.

Geological facts

Chalcedony was used as early as the Bronze Age in the Mediterranean region for making cylinder seals and jewelry. The waxy appearance is due to the microscopic fibrous structure of the quartz crystals.

Field identification & locations

Identify by its waxy luster, translucency when held to light, and lack of visible grains. Commonly found in riverbeds, volcanic fields, and desert pavements. Collectors should look for 'botryoidal' (grape-like) shapes.

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