sedimentary

Iron-stained chert or jasper

Microcrystalline quartz (SiO₂), likely colored by iron oxides/hydroxides

AI-generated identification · may be incorrect

Typically Mohs hardness 6.5–7, opaque to slightly translucent, orange-brown from hematite/goethite, with dull to waxy luster and no visible cleavage. The specimen shows a fine-grained, massive texture and a gray, possibly weathered quartz-rich band.

Identified August 17, 2026More sedimentary →

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Physical properties

Formation & geological history

Most likely formed as siliceous sediment that lithified and recrystallized into chert, later stained or replaced by iron-bearing groundwater; precise age and locality cannot be determined from the photograph. It may also be iron-rich jasper, a closely related variety.

Uses & applications

Used decoratively, in lapidary work, tumbled stones, cabochons, and occasionally as a minor aggregate. Quality depends on pattern, color, polish, and locality.

Geological facts

Jasper is an opaque variety of chalcedony/chert, while chert is microcrystalline quartz; field names often overlap. Orange coloration commonly reflects iron oxides rather than the primary quartz.

Field identification & locations

Identify it by its hardness, lack of cleavage, fine texture, and ability to scratch glass; a steel file should have difficulty scratching it. Common in iron-rich sedimentary terrains, volcanic settings, and gravel deposits worldwide.