sedimentary
Agate
Silicon dioxide (Chalcedony), SiO2
Hardness of 6.5 to 7 on the Mohs scale, exhibits orbicular or banded patterns with translucent to opaque transparency, waxy to vitreous luster, and trigonal crystal structure (microcrystalline quartz). Specific gravity is around 2.58 to 2.64.
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 of 6.5 to 7 on the Mohs scale, exhibits orbicular or banded patterns with translucent to opaque transparency, waxy to vitreous luster, and trigonal crystal structure (microcrystalline quartz). Specific gravity is around 2.58 to 2.64.
Formation & geological history
Formed primarily within cavities of volcanic and metamorphic rocks through the deposition of silica from groundwater solutions, often in concentric layers over millions of years.
Uses & applications
Widely used in ornamental objects, jewelry, tumbled stones, carvings, and precision instruments like mortars and pestles due to its durability.
Geological facts
Agate is one of the most popular stones used in lapidary arts. The name comes from the Achates River in Sicily, where agates were found in antiquity.
Field identification & locations
Can be identified in the field by its waxy luster, conchoidal fracture, characteristic concentric banding or orbicular structures, and hardness that easily scratches glass. Found worldwide, notably in Brazil, the USA, and Germany.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Quartz pebble
Silicon dioxide (SiO2)
sedimentary
Fossiliferous Concretion
Septarian Concretion containing Brachiopods/Crinoids
fossil
Sedimentary Sandstone
Arenite (Sedimentary Rock)
sedimentary
Generic Pebble / Rock Fragment
Lithic fragment / Weathered rock
sedimentary
Banded Siltstone / Mudstone Pebble
Siltstone / Argillite
sedimentary