mineral

Botryoidal chalcedony (likely agate/jasper matrix)

Microcrystalline quartz, SiO₂; commonly containing iron-oxide impurities

AI-generated identification · may be incorrect

Hardness 6.5–7; typically brown, gray, cream, and reddish, with waxy to dull luster and curved botryoidal surfaces. It has cryptocrystalline quartz structure, no cleavage, conchoidal fracture, and specific gravity near 2.6.

Identified August 15, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities or coats surfaces in volcanic rocks, building rounded chalcedony layers; iron oxides create the rusty coloration. The specimen’s exact geological age cannot be determined from the image.

Uses & applications

Used as a lapidary and ornamental material, including cabochons, carvings, polished pieces, and collector specimens; rough material has modest commercial value.

Geological facts

Botryoidal means grape-like rounded growths produced by repeated silica deposition. Surface texture and color suggest possible agate, jasper, or iron-stained chalcedony rather than a single confirmed variety.

Field identification & locations

Identify with a glassy/waxy appearance, conchoidal fracture, hardness that scratches glass, and absence of cleavage; common in volcanic districts worldwide, including Brazil, Uruguay, Mexico, and the western United States.