Where is Chalcedony found?
Chalcedony (a cryptocrystalline form of silica)
Got a photo? Identify rocks instantly with the Rockby app
Open the appChalcedony occurs in specific geological environments. Knowing where to look, and in what kind of rock, is the difference between going home empty-handed and finding a great specimen.
Where to find Chalcedony
Brazil
Significant source of various chalcedony varieties, including agate and amethyst geodes.
Uruguay
Renowned for high-quality agate and amethyst.
India
Historical source of carnelian and other chalcedony types.
Madagascar
Produces a wide range of chalcedony, including banded agate and jasper.
United States (Oregon, Washington, California, Arizona)
Various localities yield agate, jasper, and other chalcedony forms, often associated with volcanic terrains.
Germany
Idar-Oberstein region is historically famous for agate cutting and polishing.
Collecting tips
- Look in Volcanic Terrains. Chalcedony often forms in gas cavities (amygdules) within basaltic lava flows. Look for rounded or irregular nodules.
- Check Sedimentary Rocks. Examine limestone and shale outcrops for chert nodules or concretions, which are forms of chalcedony.
- Explore Riverbeds and Gravel Pits. Due to its hardness and resistance to weathering, chalcedony often survives transport and can be found as pebbles or cobbles in alluvial deposits.
- Identify Waxy Luster. A characteristic waxy to dull luster on a fresh fracture surface can be a good indicator.
- Test Hardness. Chalcedony has a Mohs hardness of 6.5-7, meaning it will scratch glass and steel.
Quick Check
- Color:
- Variable (white, gray, blue, brown, red, green)
- Luster:
- Waxy to dull
- Streak:
- White
Explore Chalcedony
Identify rocks anywhere
Free on iOS, Android, and Web. Photo identification, full database, and your personal collection.