gemstone
Agate
Silicon Dioxide (SiO2)
Hardness of 6.5 to 7 on the Mohs scale, waxy to vitreous luster, translucent to opaque transparency, microcrystalline quartz structure with distinctive banded patterns, conchoidal fracture, and specific gravity of 2.60 to 2.65.
Identified More gemstone →
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, waxy to vitreous luster, translucent to opaque transparency, microcrystalline quartz structure with distinctive banded patterns, conchoidal fracture, and specific gravity of 2.60 to 2.65.
Formation & geological history
Formed primarily within cavities of volcanic and metamorphic rocks through the deposition of silica from groundwater solutions, typically occurring in concentric layers over millions of years.
Uses & applications
Commonly used in jewelry, decorative ornaments, ornate carvings, precision instruments (such as knife-edge balances), and as collector specimens.
Geological facts
Agate was named by Theophrastus, a Greek philosopher, after the Achates River in Sicily where the stones were initially found in ancient times.
Field identification & locations
Identified by its characteristic banding, waxy texture, and conchoidal fracture. Found worldwide, particularly in regions with historic volcanic activity such as Brazil, Uruguay, India, and the western United States. Highly favored by lapidaries and rockhounds.
More like this
Other gemstone specimens
Diamond and Gold Jewelry
Carbon (Diamond) / Au (Gold)
gemstone
Ammolite
Ammolite (Biogenic Aragonite with trace elements; fossils of Placenticeras meeki and Placenticeras intercalare)
mineral
Cubic Zirconia (simulant) or Diamond
ZrO2 (Cubic Zirconia) or C (Diamond)
gemstone
Black Opal Ring (Carved Opal)
Hydrated Silicon Dioxide (SiO2·nH2O)
gemstone
Red Jasper
Silicon Dioxide (SiO2) with Hematite inclusions
sedimentary
Cubic Zirconia (or possibly Diamond)
Zirconium dioxide (or Carbon)
gemstone