mineral
Tumbled brown chalcedony or jasper
Microcrystalline quartz, SiO₂; possibly iron-bearing jasper
AI-generated identification · may be incorrectSmall, 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.
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Physical properties
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.
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.
