sedimentary
Agate
Silicon Dioxide (Chalcedony), SiO2
Hardness of 6.5-7 on the Mohs scale, variable colors due to impurities (grays, browns, whites), waxy to vitreous luster, cryptocrystalline crystal structure, conchoidal fracture with no true cleavage, and specific gravity of 2.60-2.65.
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 6.5-7 on the Mohs scale, variable colors due to impurities (grays, browns, whites), waxy to vitreous luster, cryptocrystalline crystal structure, conchoidal fracture with no true cleavage, and specific gravity of 2.60-2.65.
Formation & geological history
Forms primarily within cavities of volcanic and metamorphic rocks through the deposition of silica from groundwater solutions, often in concentric bands, over millions of years.
Uses & applications
Commonly used in ornamental items, jewelry, carvings, leather-working burnishers, and scientific instruments due to its durability.
Geological facts
Agate is one of the most popular stones used in art and healing throughout history, with archaeological recovery dating back to Neolithic peoples.
Field identification & locations
Identified by its distinctive banded appearance and waxy luster; found worldwide in regions with volcanic activity such as Brazil, India, Germany, and the United States.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Fossiliferous Concretion
Septarian Concretion containing Brachiopods/Crinoids
fossil
Quartz pebble
Silicon dioxide (SiO2)
sedimentary
Generic Pebble / Rock Fragment
Lithic fragment / Weathered rock
sedimentary
Banded Siltstone / Mudstone Pebble
Siltstone / Argillite
sedimentary
Sedimentary Sandstone
Arenite (Sedimentary Rock)
sedimentary