sedimentary
Agate Nodule
Chalcedony (SiO2)
Hardness of 6.5 to 7 on the Mohs scale, color ranges from reddish-brown, pink, to white, vitreous to waxy luster, microcrystalline (cryptocrystalline) quartz structure, conchoidal fracture with no true cleavage, and specific gravity of 2.60 to 2.65.
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, color ranges from reddish-brown, pink, to white, vitreous to waxy luster, microcrystalline (cryptocrystalline) quartz structure, conchoidal fracture with no true cleavage, and specific gravity of 2.60 to 2.65.
Formation & geological history
Formed through the deposition of silica from groundwater solutions, typically in cavities of volcanic or sedimentary rocks, over millions of years.
Uses & applications
Used in ornamental objects, jewelry, lapidary art, and as collector specimens.
Geological facts
Agate forms in concentric bands around a cavity wall, reflecting changes in the water chemistry and silica concentration during its formation.
Field identification & locations
Identified by its waxy luster, microcrystalline texture, and distinct banding or nodular habit. Commonly found worldwide in volcanic regions, riverbeds, and desert areas.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Sedimentary Sandstone
Arenite (Sedimentary Rock)
sedimentary
Fossiliferous Concretion
Septarian Concretion containing Brachiopods/Crinoids
fossil
Banded Siltstone / Mudstone Pebble
Siltstone / Argillite
sedimentary
Shale (or Mudstone/Siltstone)
Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)
sedimentary
Shale
Shale (clastic sedimentary rock)
sedimentary