mineral

Tumbled yellow-brown quartz/chert fragment

Microcrystalline quartz (SiO₂), possibly jasper or chalcedony

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; honey-yellow to brown, translucent to opaque, with a waxy-to-dull luster and irregular conchoidal fracture. The small rounded shape suggests tumbling or natural abrasion; crystal structure is cryptocrystalline, with no visible cleavage.

Identified August 14, 2026More mineral →

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Physical properties

Formation & geological history

Likely formed when silica-rich groundwater replaced or cemented sediment, producing chert, jasper, or chalcedony; exact age and locality cannot be determined from the image. Such material occurs in sedimentary beds, volcanic cavities, and stream gravels.

Uses & applications

Used as lapidary material for cabochons, beads, carvings, and decorative stone; common pieces have modest collecting value.

Geological facts

Yellow coloration may result from iron oxides or hydroxides. Distinguishing jasper from ordinary chert or chalcedony generally requires close examination of translucency, texture, and composition.

Field identification & locations

Common in gravels and sedimentary regions worldwide, including the western United States, Mexico, Brazil, and Australia. A glassy fracture, lack of cleavage, and ability to scratch ordinary glass support quartz; a streak test is usually white.