mineral

Tumbled brown chalcedony or jasper

Microcrystalline quartz, SiO₂; possibly iron-bearing jasper

AI-generated identification · may be incorrect

Small, polished fragment with brown to olive-brown color, waxy-to-subvitreous luster, and no visible cleavage. Quartz hardness is about 7 Mohs; specific gravity is approximately 2.6, though the photo cannot confirm exact variety.

Identified September 12, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich groundwater fills cavities or fractures and precipitates microcrystalline quartz, often with iron oxides producing brown coloration. Such material may range from ancient volcanic-hosted deposits to younger sedimentary replacements.

Uses & applications

Used for cabochons, beads, carvings, tumbling, and ornamental objects; lower-grade pieces are inexpensive lapidary material.

Geological facts

Chalcedony is quartz made of microscopic interlocking fibers, while jasper is opaque, impurity-rich chalcedony. The specimen appears human-tumbled or polished rather than naturally weathered.

Field identification & locations

Identify by its smooth polish, opacity, quartz-like hardness, and lack of cleavage; it should scratch glass but not be scratched by a steel knife. Common sources include Brazil, India, Madagascar, Uruguay, and the western United States.