sedimentary
Agate
Silicon Dioxide (Chalcedony), SiO2
Hardness of 6.5 to 7 on the Mohs scale, variable colors due to impurities, waxy to vitreous luster, microcrystalline (cryptocrystalline) quartz structure with no distinct cleavage, 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, variable colors due to impurities, waxy to vitreous luster, microcrystalline (cryptocrystalline) quartz structure with no distinct cleavage, specific gravity of 2.60 to 2.65.
Formation & geological history
Forms primarily within cavities of volcanic and metamorphic rocks through the slow deposition of silica-rich groundwater solutions over millions of years.
Uses & applications
Used in ornamental objects, jewelry, lapidary arts, precision instruments, and mortar and pestle sets.
Geological facts
Agate is one of the most popular stones used in art and lapidary work, with banded varieties historically prized as talismans and amulets dating back to ancient civilizations like the Greeks and Egyptians.
Field identification & locations
Identified by its distinctive concentric banding, waxy luster, and conchoidal fracture. Commonly found in regions with past volcanic activity worldwide.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Quartz pebble
Silicon dioxide (SiO2)
sedimentary
Fossiliferous Concretion
Septarian Concretion containing Brachiopods/Crinoids
fossil
Generic Pebble / Rock Fragment
Lithic fragment / Weathered rock
sedimentary
Sedimentary Sandstone
Arenite (Sedimentary Rock)
sedimentary
Banded Siltstone / Mudstone Pebble
Siltstone / Argillite
sedimentary