sedimentary
Agate
Silicon dioxide (Chalcedony), SiO2
AI-generated identification · may be incorrectHardness of 6.5 to 7 on the Mohs scale, colors vary widely including white, gray, blue, red, orange, and brown, waxy to vitreous luster, microcrystalline (cryptocrystalline) quartz structure, conchoidal fracture, specific gravity of 2.60 to 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 to 7 on the Mohs scale, colors vary widely including white, gray, blue, red, orange, and brown, waxy to vitreous luster, microcrystalline (cryptocrystalline) quartz structure, conchoidal fracture, specific gravity of 2.60 to 2.65.
Formation & geological history
Formed mainly in cavities of volcanic and metamorphic rocks through the deposition of silica from groundwater solutions in concentric layers over long periods.
Uses & applications
Used in ornamental objects, jewelry, polished specimens, mortar and pestle sets, and as a popular collector mineral.
Geological facts
Agate is one of the most popular stones used in art and lapidary work. It was named by Theophrastus, a Greek philosopher, after the Achates river in Sicily.
Field identification & locations
Easily identified by its characteristic banded patterns and waxy luster. Common in volcanic regions worldwide, particularly in Brazil, Uruguay, India, and the western United States.
More like this
Other sedimentary specimens
Fossiliferous Sedimentary Rock
Sedimentary limestone with invertebrate fossil imprint
fossil
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sandstone
Arenite
sedimentary
Quartz pebble
Silicon dioxide (SiO2)
sedimentary
Generic Pebble / Rock Fragment
Lithic fragment / Weathered rock
sedimentary
Shale
Shale (clastic sedimentary rock)
sedimentary