mineral

Tumbled jasper or chalcedony

Microcrystalline quartz, SiO₂; likely opaque jasper with chalcedonic zones

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; rounded and polished, with cream, tan, honey-brown, and gray patches, earthy translucence, and a waxy to glassy luster. Quartz has a trigonal crystal structure but is cryptocrystalline here; cleavage is absent and fracture is conchoidal.

Identified August 29, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities or replaces volcanic and sedimentary material, commonly developing iron-oxide brown coloration. The specimen is geologically ancient, but its exact age and locality cannot be determined from the image.

Uses & applications

Used as inexpensive lapidary material for cabochons, beads, carvings, and decorative stones; polished pieces commonly sell for a few dollars.

Geological facts

Jasper is an opaque variety of chalcedony, while more translucent portions may be agate-like. Iron oxides produce the yellow-brown staining.

Field identification & locations

Identify by its very hard, nonmetallic surface, lack of cleavage, waxy appearance, and inability to scratch with a steel knife; quartz should scratch glass. Common worldwide, especially in volcanic terrains; avoid confusing it with dyed or resin-treated material.