mineral

Yellow Chalcedony (Agate/Chert)

Cryptocrystalline Quartz (SiO2)

Hardness: 6.5-7 (Mohs scale), Color: Waxy yellowish-brown, Luster: Vitreous to waxy, Crystal structure: Trigonal/Microcrystalline, Cleavage: None (Conchoidal fracture), Specific Gravity: 2.60-2.64

Hardness: 6

Identified June 11, 2026More mineral →

Identify your own rocks.

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

App Store Google Play

Physical properties

Hardness: 6.5-7 (Mohs scale), Color: Waxy yellowish-brown, Luster: Vitreous to waxy, Crystal structure: Trigonal/Microcrystalline, Cleavage: None (Conchoidal fracture), Specific Gravity: 2.60-2.64

Formation & geological history

Formed by the deposition of silica-rich fluids in cavities or veins of volcanic or sedimentary rocks. This specimen appears water-worn, likely tumbled in a river or beach environment.

Uses & applications

Used for lapidary work, jewelry (cabochons), historical tool making (flaking), and as a collector's specimen.

Geological facts

Yellow chalcedony is often found in riverbeds. Its waxy appearance and smooth texture are characteristic of microcrystalline quartz varieties that have been weathered over long periods.

Field identification & locations

Identify in the field by its translucency, waxy surface texture, conchoidal (shell-like) fracture patterns, and inability to be scratched by a steel knife. Common in volcanic regions and gravel deposits.

Other mineral specimens

See all

Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Schist

Metamorphic

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

Biotite Schist

Biotite-rich Schist [K(Mg,Fe)3AlSi3O10(F,OH)2]

metamorphic