mineral

Brown chalcedony (likely agate/jasper)

Chalcedony, cryptocrystalline SiO₂, with iron-oxide inclusions

AI-generated identification · may be incorrect

Typically hardness 6.5–7 Mohs, translucent brown to honey-orange, waxy to vitreous luster, and no visible cleavage; the rough, porous surface may contain quartz-lined cavities and iron staining. The specimen appears partly banded, suggesting agate, with opaque zones resembling jasper.

Identified August 16, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities and fractures in volcanic rock, depositing microcrystalline quartz in layers; iron oxides create the brown-red colors. Formation is generally Cenozoic or older, depending on its host volcanic rock.

Uses & applications

Used for cabochons, beads, carvings, polished slabs, and ornamental objects; durable varieties are also used as gemstones and abrasives.

Geological facts

Agate and jasper are varieties of chalcedony distinguished mainly by translucency and pattern: agate is commonly translucent and banded, while jasper is opaque and impure.

Field identification & locations

Identify by its waxy luster, conchoidal fracture, silica hardness, and lack of cleavage; common sources include Brazil, Uruguay, Mexico, India, Madagascar, and the western United States. Exact identification would benefit from examining translucency, banding, and a fresh fracture.