Rock Identifier
Tumbled amber-colored chalcedony or jasper (Microcrystalline quartz (SiO₂), likely iron-stained chalcedony/jasper) — mineral
mineral

Tumbled amber-colored chalcedony or jasper

Microcrystalline quartz (SiO₂), likely iron-stained chalcedony/jasper

AI-generated identification · may be incorrect

Opaque honey-brown, waxy to dull luster, smoothly tumbled with pale flowing bands or fractures; Mohs hardness about 6.5–7, no visible cleavage, cryptocrystalline quartz structure. The image alone cannot distinguish chalcedony from jasper or another yellow-brown silica material with certainty.

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Physical properties

Opaque honey-brown, waxy to dull luster, smoothly tumbled with pale flowing bands or fractures; Mohs hardness about 6.5–7, no visible cleavage, cryptocrystalline quartz structure. The image alone cannot distinguish chalcedony from jasper or another yellow-brown silica material with certainty.

Formation & geological history

Forms when silica-rich groundwater fills cavities, fractures, or volcanic vesicles; iron oxides produce the orange-brown color. Such silica deposits range from Precambrian to Cenozoic in age.

Uses & applications

Used for cabochons, beads, carvings, lapidary specimens, and occasionally decorative stone; generally inexpensive as a tumbled piece.

Geological facts

Jasper is the opaque, impurity-rich variety of chalcedony, while chalcedony is typically more translucent. Surface polish and lighting can make identification by photograph difficult.

Field identification & locations

Commonly found in volcanic and sedimentary terrains worldwide, including Brazil, India, Madagascar, Mexico, and the western United States. A glassy fracture, resistance to scratching by steel, and lack of fizz with dilute acid support quartz-rich material; exact identification requires testing.