sedimentary

Iron-rich jasper/chert nodule

Microcrystalline quartz (SiO₂) with iron oxides/hydroxides, likely hematite and goethite

AI-generated identification · may be incorrect

Opaque brown, tan, gray, and reddish material with earthy-to-waxy luster and irregular conchoidal-looking surfaces; quartz hardness about 6.5–7 Mohs, no cleavage, specific gravity roughly 2.6–2.7. The rounded, glossy appearance may indicate natural weathering or polishing.

Identified September 6, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed when silica-rich sediment or volcanic material was replaced/cemented by microcrystalline quartz, with later iron staining; commonly Paleozoic to younger, depending on locality. Exact identification and age require locality and testing.

Uses & applications

Used as lapidary rough, cabochons, carvings, and decorative stone; jasper is generally inexpensive unless unusually patterned or from a notable locality.

Geological facts

The contrasting bands and patches result mainly from variable iron-oxide content and silica replacement. A steel file should not scratch fresh quartz-rich surfaces, while streak testing may produce a yellow-brown or reddish powder.

Field identification & locations

Common in weathered sedimentary formations, river gravels, and volcanic terrains worldwide, especially areas with iron-rich groundwater. Confirm with a hardness test, streak, and magnification; similar material may be iron-stained quartz or silicified rock.