gemstone

Dyed and polished gemstone chips

Mostly chalcedony (microcrystalline quartz, SiO₂), with probable amethyst and agate varieties

AI-generated identification · may be incorrect

Tumbled, smooth, vitreous-to-waxy luster; purple pieces are likely amethyst or dyed chalcedony, blue likely dyed chalcedony, gray/white pieces likely quartz or agate. Quartz hardness is Mohs 7; specific gravity about 2.6; no obvious cleavage. One dark brown piece may be jasper or another opaque chalcedony.

Identified August 19, 2026More gemstone →

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Physical properties

Formation & geological history

These are likely natural silica-rich stones shaped by weathering and then machine-tumbled and possibly dyed; quartz formed in volcanic cavities or hydrothermal veins, commonly during the Mesozoic–Cenozoic. Such material is plausible around São Paulo, Brazil, where weathered crystalline rocks and quartz-bearing veins occur, though the exact source cannot be determined visually.

Uses & applications

Low-cost jewelry, craft supplies, décor, and lapidary practice; natural amethyst and agate pieces may have modest collector appeal.

Geological facts

Strongly saturated blue and violet colors, especially in small uniform tumbled stones, commonly indicate dye treatment. Amethyst is purple quartz colored mainly by iron and irradiation.

Field identification & locations

Look for color concentrated in cracks, pits, or edges as evidence of dye; a glassy luster, conchoidal fracture, and lack of cleavage support quartz/chalcedony. Estimated value: about $1–$5 for this mixed handful; individually, roughly $0.50–$10 depending on natural color, size, and quality.