mineral

Banded agate (likely moss/iron-stained agate)

Microcrystalline quartz, primarily chalcedony (SiO₂), with iron-oxide inclusions

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent blue-gray to gray-white bands with rusty orange-brown iron staining and possible mossy inclusions; waxy to vitreous luster; cryptocrystalline quartz, without visible cleavage; specific gravity about 2.6.

Identified September 10, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater repeatedly fills cavities in volcanic rocks, depositing chalcedony in successive bands; iron oxides create the brown-orange areas. Usually Cenozoic to older volcanic-host-rock material, with age dependent on locality.

Uses & applications

Commonly cut and polished for cabochons, slices, carvings, and ornamental objects; rough pieces are inexpensive collector specimens.

Geological facts

The apparent bands are chalcedony growth layers rather than sedimentary bedding. Rusty zones may contain goethite, hematite, or other iron oxides, while open cavities can contain quartz crystals.

Field identification & locations

Identify by its waxy translucent appearance, curved/concentric banding, very high hardness, and inability to scratch with a steel knife easily; it commonly occurs in volcanic regions worldwide, including Brazil, Uruguay, Mexico, India, and the western United States.