mineral

Tumbled jasper or chert (tentative)

Microcrystalline quartz, SiO₂, likely opaque chalcedony/jasper

AI-generated identification · may be incorrect

Small rounded, polished pebble with brown, tan, gray, and cream mottling; vitreous-to-waxy luster and no visible crystal faces. Quartz hardness is about 7 Mohs; specific gravity is approximately 2.6, with conchoidal fracture rather than cleavage.

Identified August 29, 2026More mineral →

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Physical properties

Formation & geological history

Likely formed when silica-rich groundwater replaced or cemented sediment, producing cryptocrystalline quartz; its exact geological age and locality cannot be determined from the image. Tumbled surfaces obscure natural textures and diagnostic features.

Uses & applications

Used as a lapidary stone for tumbled specimens, cabochons, beads, and decorative objects; common pieces have modest collecting value.

Geological facts

The stone could also be a low-grade agate, jasper, or silicified rock; color alone is insufficient for confident identification.

Field identification & locations

Commonly found in silica-rich gravels and volcanic or sedimentary terrains worldwide. Test with a steel file or quartz point, inspect for translucent banding, and use streak, density, or magnification tests; avoid damaging valuable specimens.