mineral

Agate

Silicon Dioxide (Quartz), SiO2

Hardness: 6.5 to 7 on the Mohs scale. Color: Varies widely, often grayish, white, translucent, brown, or banded. Luster: Vitreous to waxy. Crystal structure: Trigonal (microcrystalline quartz/chalcedony). Cleavage: None (exhibits conchoidal fracture). Specific gravity: 2.60 to 2.65.

Hardness: 6
Luster: Vitreous to waxy

Identified August 3, 2026More mineral →

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Physical properties

Formation & geological history

Formed primarily within volcanic and metamorphic rocks through the deposition of silica from groundwater in cavities or vesicles, often in concentric layers over millions of years.

Uses & applications

Used extensively in making jewelry, ornamental carvings, polished specimens, decorative objects, and historically for precision instruments like mortar and pestles.

Geological facts

Agate is one of the most popular and varied forms of chalcedony. The name comes from the Dirilo River (now the Achates) in Sicily, where agates were found in ancient times.

Field identification & locations

Easily identified by its waxy luster, conchoidal fracture, and often translucent banded appearance. Found worldwide in regions with volcanic activity such as Brazil, India, Germany, and the USA.