metamorphic

Tumbled jasper (likely yellow/brecciated jasper)

Microcrystalline quartz/chalcedony, SiO₂, with iron-oxide and clay inclusions

AI-generated identification · may be incorrect

Opaque, yellow-brown and gray mottling with reddish iron staining; polished waxy-to-dull luster and no visible crystal faces. Mohs hardness about 6.5–7; cryptocrystalline quartz, with indistinct fracture and specific gravity near 2.6.

Identified September 5, 2026More metamorphic →

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Physical properties

Formation & geological history

Jasper forms when silica-rich fluids replace or cement volcanic ash, sediments, or altered rock, while iron oxides create the yellow-red colors. The specimen’s precise geological age and locality cannot be determined from the photograph.

Uses & applications

Used for inexpensive cabochons, beads, carvings, lapidary objects, and decorative stone; it has little industrial use compared with ordinary quartz aggregates.

Geological facts

Jasper is an opaque variety of chalcedony and is commonly grouped with quartz despite its often mixed geological origin. Color patterns are produced mainly by iron oxides and other impurities.

Field identification & locations

Identify it by opacity, dense fine grain, quartz-like hardness, and resistance to scratching by a steel blade; it should not fizz in dilute acid. Common sources include India, Madagascar, Brazil, Australia, Mexico, and the western United States.