sedimentary
Agate
Silicon Dioxide (Chalcedony), SiO2
AI-generated identification · may be incorrectHardness of 6.5 to 7 on the Mohs scale, waxy to vitreous luster, cryptocrystalline crystal structure, conchoidal fracture with no true cleavage, and a specific gravity of 2.58 to 2.64. Colors vary widely due to impurities, often showing banded patterns of white, grey, red, orange, and brown.
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, waxy to vitreous luster, cryptocrystalline crystal structure, conchoidal fracture with no true cleavage, and a specific gravity of 2.58 to 2.64. Colors vary widely due to impurities, often showing banded patterns of white, grey, red, orange, and brown.
Formation & geological history
Forms primarily within cavities of volcanic and metamorphic rocks through the deposition of silica from groundwater solutions, often layer by layer over millions of years.
Uses & applications
Used in ornamental objects, jewelry, lapidary arts, precision instruments, and as collectible mineral specimens.
Geological facts
Agate has been used since antiquity for gemstones, seals, and amulets, notably by the ancient Greeks and Romans. It is often associated with balancing emotional and physical energy.
Field identification & locations
Can be identified by its distinctive concentric banding, waxy luster, and translucency. Found globally, especially in regions with historic volcanic activity like Brazil, India, Germany, and the USA.
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
Shale
Shale (clastic sedimentary rock)
sedimentary
Shale (or Mudstone/Siltstone)
Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)
sedimentary