sedimentary
Agate
Silicon Dioxide (Chalcedony), SiO2
Hardness: 6.5-7 on the Mohs scale; Colors vary widely including white, grey, blue, red, orange, and yellow; Luster: Waxy to vitreous; Crystal structure: Trigonal (microcrystalline quartz); Cleavage: None
- Hardness
- 6
- Luster
- Waxy to vitreous
Identified More sedimentary →
Explore Agate in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6.5-7 on the Mohs scale; Colors vary widely including white, grey, blue, red, orange, and yellow; Luster: Waxy to vitreous; Crystal structure: Trigonal (microcrystalline quartz); Cleavage: None
Formation & geological history
Formed primarily within cavities of volcanic and metamorphic rocks through the deposition of silica-rich groundwater solutions in concentric layers over millions of years.
Uses & applications
Used extensively in jewelry, ornamental carvings, polished display specimens, and industrial bearings or mortars due to its hardness.
Geological facts
Agate is one of the most popular materials used in lapidary work and was highly prized in ancient civilizations like the Greeks and Egyptians for signet rings and talismans.
Field identification & locations
Found worldwide in volcanic rock cavities and river gravels. Easily identified by its banded patterns and waxy luster.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Quartz pebble
Silicon dioxide (SiO2)
sedimentary
Generic Pebble / Rock Fragment
Lithic fragment / Weathered rock
sedimentary
Sedimentary Sandstone
Arenite (Sedimentary Rock)
sedimentary
Fossiliferous Concretion
Septarian Concretion containing Brachiopods/Crinoids
fossil
Banded Siltstone / Mudstone Pebble
Siltstone / Argillite
sedimentary