sedimentary

Banded Agate

Silicon Dioxide (SiO2) - Cryptocrystalline Quartz

Hardness: 6.5-7.0 (Mohs scale); Color: Purple, lavender, and white bands; Luster: Vitreous to waxy when polished; Crystal Structure: Trigonal (microcrystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.58-2.64

Hardness: 6
Color: Purple, lavender, and white bands
Luster: Vitreous to waxy when polished

Identified July 10, 2026More sedimentary →

Explore Banded Agate in the encyclopedia →

Identify your own rocks.

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

App Store Google Play

Physical properties

Formation & geological history

Formed in cavities of volcanic or sedimentary rocks through the gradual deposition of silica from groundwater. The bands represent different pulses of mineral-rich fluids over thousands of years.

Uses & applications

Commonly used for lapidary arts, jewelry, tumbled stones, decorative ornaments, and metaphysical collecting.

Geological facts

The distinct banding is caused by variations in trace mineral impurities, such as iron or manganese, during the deposition process. Agates have been used for amulets and ornaments since the era of Ancient Greece.

Field identification & locations

Identified by its waxy luster, translucency when held to light, and characteristic parallel banding. It is often found in riverbeds or near volcanic outcrops in regions like Brazil, Botswana, and the USA.

Other sedimentary specimens

See all

Sandstone or Siltstone

Arenite (if sandstone)

Sedimentary

Mudstone

Argillite / Siliciclastic sedimentary rock

sedimentary

Cone-in-cone structure (Limestone)

Cone-in-cone structure (Secondary Sedimentary Structure)

sedimentary

Brown Sandstone (River Rock)

Arenite

sedimentary

Sandstone Grain

Clastic Sedimentary Rock Grain (SiO2 dominated)

sedimentary

Chert Breccia

Brecciated Chert (Microcrystalline Silica)

sedimentary