Rock Identifier
Tumbled orange jasper or iron-rich chert (Microcrystalline quartz (SiO₂), colored by iron oxides) — mineral
mineral

Tumbled orange jasper or iron-rich chert

Microcrystalline quartz (SiO₂), colored by iron oxides

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; opaque orange-red, earthy/waxy luster, very fine-grained cryptocrystalline quartz, with no visible cleavage and conchoidal fracture. The smooth surface indicates tumbling or polishing.

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Physical properties

Hardness about 6.5–7 Mohs; opaque orange-red, earthy/waxy luster, very fine-grained cryptocrystalline quartz, with no visible cleavage and conchoidal fracture. The smooth surface indicates tumbling or polishing.

Formation & geological history

Forms when silica-rich groundwater replaces or cements sediment, while hematite/goethite produces the orange-red color; commonly Precambrian to younger. Exact identification and age require testing or locality information.

Uses & applications

Used for cabochons, beads, carvings, ornamental stones, and inexpensive collecting specimens; occasionally used as decorative aggregate.

Geological facts

Jasper is a variety of opaque chert distinguished mainly by abundant impurities and color. Its color may darken or become more red with increased iron-oxide content.

Field identification & locations

Identify by its opaque uniform color, glassy-to-waxy surface, high hardness, and inability to scratch with a steel knife easily; quartz-rich jasper should scratch glass. Common in volcanic and sedimentary terrains worldwide, including India, Madagascar, Brazil, and the western United States.