mineral

Rough agate (likely banded chalcedony)

Microcrystalline quartz, SiO₂; chalcedony with iron-oxide color banding

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; waxy to vitreous luster, translucent yellow-tan areas with reddish-brown bands, and no visible cleavage. The specimen appears massive and may show curved or irregular banding; crystal structure is trigonal quartz at microscopic scale.

Identified October 16, 2026More mineral →

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Physical properties

Formation & geological history

Agate forms as silica-rich fluids fill cavities and deposit successive layers, often in volcanic rocks; iron oxides create red and brown colors. Formation age depends on its source and cannot be determined from the photograph.

Uses & applications

Used for cabochons, beads, carvings, ornaments, and polished display pieces; agate is also used in some precision components.

Geological facts

Agate is a variety of chalcedony, not a separate mineral species; its bands can record changing conditions during silica deposition.

Field identification & locations

Look for hardness near 7, a waxy surface, and layered or curved color bands; common sources include Brazil, Uruguay, India, and the western United States. The image alone cannot establish the exact variety or locality.