mineral

Tumbled jasper or chert

Microcrystalline quartz (SiO₂), likely jasper/chert

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; mustard-yellow to brown, opaque, with a wet glassy-to-waxy luster and no obvious cleavage. The rounded shape is artificially tumbled; color may reflect iron-oxide impurities.

Identified August 14, 2026More mineral →

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Physical properties

Formation & geological history

Formed when silica-rich groundwater replaced or cemented sediments, commonly with iron staining; such material can range from Paleozoic to recent in age. Exact locality and age cannot be determined from the photograph.

Uses & applications

Used as an inexpensive lapidary stone for cabochons, carvings, beads, and polished decor; generally not suitable as a major construction stone.

Geological facts

Jasper is an opaque variety of chalcedony, while chert is typically finer-grained and may be more uniformly colored. A scratch test with steel and glass can help distinguish it from softer look-alikes.

Field identification & locations

Common in sedimentary environments and stream gravels worldwide, including the western United States, Mexico, India, Madagascar, and Australia. Confirm with hardness, a white streak, and magnification showing microcrystalline quartz rather than glass or plastic.