mineral

Botryoidal Chalcedony (Agate)

Cryptocrystalline Quartz (SiO2)

Hardness: 6.5-7.0 (Mohs scale); Color: White, translucent, with orange/carnelian banding; Luster: Waxy to vitreous; Crystal Structure: Trigonal (microscopic); Cleavage: None (conchoidal fracture); Specific Gravity: 2.58–2.64

Hardness: 6
Color: White, translucent, with orange/carnelian banding
Luster: Waxy to vitreous

Identified June 24, 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

Secondary formation in volcanic or sedimentary rock cavities. It forms when silica-rich hydrothermal fluids precipitate in voids or vugs, often creating 'grape-like' or botryoidal structures over thousands of years. This piece specifically shows features of agate with carnelian-colored iron oxide staining.

Uses & applications

Commonly used as gemstones for jewelry (cabochons), lapidary work, ornamental carvings, and as a popular specimen for mineral collectors due to its unique patterns.

Geological facts

While it appears opaque or solid white, chalcedony is actually composed of micro-fibrous quartz. The orange hue seen in the corner is caused by trace amounts of iron oxide, typically classifying that specific section as carnelian.

Field identification & locations

Identify in the field by its waxy luster, hardness (it will scratch glass), and typical botryoidal (rounded) surface texture. Often found in riverbeds or eroding out of volcanic basalt flows in locations like Oregon, Washington, or Brazil.

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

Green Apatite on Albite

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

mineral