sedimentary
Agate Nodule
Silicon Dioxide (Chalcedony), SiO2
Hardness of 6.5 to 7 on the Mohs scale, waxy to vitreous luster, cryptocrystalline structure, conchoidal fracture, and specific gravity of 2.58 to 2.64. Colors vary widely due to impurities, often showing banded or concentric patterns.
Identified More sedimentary →
Explore Agate Nodule 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 structure, conchoidal fracture, and specific gravity of 2.58 to 2.64. Colors vary widely due to impurities, often showing banded or concentric patterns.
Formation & geological history
Formed in cavities of volcanic or sedimentary rocks through the deposition of silica from groundwater solutions over millions of years.
Uses & applications
Used in ornamental objects, jewelry, tumbled stones, small carvings, and laboratory mortars and pestles.
Geological facts
Agate is one of the most popular lapidary materials in the world, known for its incredible variety of colorful bands and inclusions formed in ancient volcanic gas bubbles or rock cavities.
Field identification & locations
Found worldwide in volcanic and sedimentary regions. Collectors look for unique banding, orbicular patterns, or transparency. Often found in riverbeds and eroded gravels as weathered pebbles.
More like this
Other sedimentary specimens
Fossiliferous Sedimentary Rock
Sedimentary limestone with invertebrate fossil imprint
fossil
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