sedimentary

Yellow jasper / iron-rich chert

Microcrystalline quartz (SiO₂), commonly colored by iron oxides

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; yellow-gold opaque body with gray-black translucent-looking central material, dull to waxy luster, and conchoidal fracture. No visible cleavage; likely very fine-grained quartz with iron-oxide inclusions.

Identified September 7, 2026More sedimentary →

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Physical properties

Formation & geological history

Most likely silicified sediment or chemically precipitated chert formed when silica replaced sedimentary material, with later iron staining. Exact geological age cannot be determined from the photograph; such material occurs from Precambrian to relatively young sedimentary settings.

Uses & applications

Used as lapidary rough, cabochons, beads, carvings, and ornamental stone; occasionally collected for its contrasting yellow and dark interior. It has little industrial value as an isolated specimen.

Geological facts

The angular break and waxy appearance are characteristic of chert or jasper rather than a crystalline mineral. Dark areas may reflect impurities, manganese/iron oxides, or a different silica-rich zone.

Field identification & locations

Look for very fine texture, lack of visible grains, conchoidal fracture, and inability to scratch it with a steel knife; quartz should scratch glass. Common sources include Arizona, Oregon, California, Brazil, and India, but locality cannot be established visually.