mineral

Agate

Silicon dioxide (SiO2)

Hardness: 6.5-7 (Mohs scale), Color: Multicolored (red, white, blue, brown, grey), Luster: Waxy to vitreous, Structure: Cryptocrystalline, Fracture: Conchoidal, Specific Gravity: 2.58-2.64

Hardness: 6

Identified April 5, 2026More mineral →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Hardness: 6.5-7 (Mohs scale), Color: Multicolored (red, white, blue, brown, grey), Luster: Waxy to vitreous, Structure: Cryptocrystalline, Fracture: Conchoidal, Specific Gravity: 2.58-2.64

Formation & geological history

Formed in cavities of volcanic rocks or ancient lavas, where silica-rich groundwater deposited layers of chalcedony over time. These range from recent geological periods to billions of years old.

Uses & applications

Used primarily in jewelry, lapidary arts, ornamental carvings, and historically for precision instruments like mortars and pestles or scale pivots due to its hardness.

Geological facts

Agates are traditionally associated with healing and strength. Many are named after their appearance, such as Fire Agate, Moss Agate, or Lace Agate. They are the state rock of several US states including Minnesota and South Dakota.

Field identification & locations

Identify in the field by their waxy luster, band patterns (when broken), and translucent qualities. Commonly found in riverbeds, glacial tills, and volcanic regions worldwide.