sedimentary
Agate
Silicon Dioxide (Chalcedony), SiO2
Hardness: 6.5-7 on the Mohs scale; Color: Brown, tan, translucent; Luster: Waxy to vitreous; Crystal structure: Microcrystalline (trigonal); Cleavage: None, exhibits conchoidal fracture; Specific gravity: 2.58-2.64
- Hardness
- 6
- Color
- Brown, tan, translucent
- Luster
- Waxy to vitreous
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: 6.5-7 on the Mohs scale; Color: Brown, tan, translucent; Luster: Waxy to vitreous; Crystal structure: Microcrystalline (trigonal); Cleavage: None, exhibits conchoidal fracture; Specific gravity: 2.58-2.64
Formation & geological history
Formed within the cavities of volcanic and metamorphic rocks through the deposition of silica-rich groundwater solutions over millions of years.
Uses & applications
Used in jewelry, ornamental carvings, polished specimens, scientific instruments, and by collectors.
Geological facts
Agate is a common form of chalcedony that often displays distinct banding patterns, though solid colored variations also occur. Ancient civilizations used it for talismans and seals.
Field identification & locations
Identified by its waxy luster, conchoidal fracture, and resistance to scratching by steel. Commonly found in riverbeds, beaches, and volcanic regions worldwide.
More like this
Other sedimentary specimens
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
Sedimentary Sandstone
Arenite (Sedimentary Rock)
sedimentary
Banded Siltstone / Mudstone Pebble
Siltstone / Argillite
sedimentary