mineral

Tumbled jasper or chalcedony pebble

Microcrystalline quartz (SiO₂), likely jasper/chalcedony with iron-oxide staining

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; opaque gray-green and honey-brown areas, vitreous to waxy luster, irregular conchoidal fracture, and no visible cleavage. The glossy surface indicates tumbling or polishing.

Identified August 11, 2026More mineral →

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Physical properties

Formation & geological history

Likely formed when silica-rich groundwater filled cavities or fractures, with iron and other impurities producing the brown and green colors; commonly Precambrian to younger, depending on source. Exact identification requires testing or a fresh surface.

Uses & applications

Used for inexpensive cabochons, beads, carvings, and lapidary specimens; mainly valued decoratively rather than industrially.

Geological facts

Jasper is an opaque variety of quartz, while chalcedony is typically translucent; mixed specimens can grade between the two. Color zoning often reflects changing groundwater chemistry during formation.

Field identification & locations

Common sources include volcanic terrains and sedimentary silica deposits worldwide, especially Brazil, Madagascar, India, Australia, and the western United States. Quartz hardness, lack of cleavage, and resistance to scratching help distinguish it from softer glassy or carbonate material.