
mineral
Banded Agate (Tumbled)
Cryptocrystalline Quartz (SiO2)
Hardness: 6.5–7 (Mohs scale); Color: Variegated bands of brown, black, grey, and white; Luster: Vitreous to waxy; Crystal structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific gravity: 2.58–2.64.
- Hardness
- 6
- Color
- Variegated bands of brown, black, grey, and white
- Luster
- Vitreous to waxy
Identified More mineral →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6.5–7 (Mohs scale); Color: Variegated bands of brown, black, grey, and white; Luster: Vitreous to waxy; Crystal structure: Hexagonal (trigonal); Cleavage: None (conchoidal fracture); Specific gravity: 2.58–2.64.
Formation & geological history
Formed in volcanic rock cavities or ancient sedimentary layers where silica-rich groundwater deposits layers of rhythmic crystallization over thousands of years. Common in Cenozoic era basaltic flows.
Uses & applications
Used primarily in lapidary arts for jewelry, beads, and cabochons. Long history of use in making burnishing tools, mortar and pestles, and ornamental carvings.
Geological facts
Ancient Romans believed agate helped with harvests and protection. Its distinct banding is known as 'Liesegang rings,' caused by the periodic precipitation of minerals within the silica gel.
Field identification & locations
Identify by its characteristic colorful banding and translucent to opaque edges when held to light. Common in Brazil, India, and lake shores in the Northern US. Tumbled pieces are very smooth and rounded.
More like this
Other mineral specimens
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