sedimentary

Polished jasper or chert nodule

Microcrystalline quartz (SiO₂), likely iron-stained jasper/chert

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; opaque cream, brown, and reddish bands with a dull to waxy luster and no visible cleavage. Its rounded, dense form and conchoidal-looking edges are typical of siliceous nodules.

Identified August 28, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed when silica-rich groundwater replaced or cemented sediment, commonly with iron-oxide staining; the exact geological age cannot be determined from the image. Weathering rounded the nodule, and the surface appears naturally smooth or lightly polished.

Uses & applications

Used as a decorative stone, lapidary material, cabochons, beads, and small carvings; tougher varieties can serve as minor aggregate or toolstone.

Geological facts

Jasper and chert are varieties of cryptocrystalline quartz, so individual quartz crystals are generally invisible. Red and brown colors usually reflect hematite or other iron oxides.

Field identification & locations

Identify by testing for glass-scratching hardness, dense fine-grained texture, and conchoidal fracture; it is commonly found in sedimentary beds, gravel deposits, and stream cobbles worldwide. Exact identification would benefit from a fresh surface or streak test.