igneous
Jasper and Basalt River Pebble
Silica-rich volcanic rock with iron oxide staining
Hardness of 6.5-7 on the Mohs scale, colors ranging from dark grey to brownish-orange, dull to waxy luster, microcrystalline structure, conchoidal fracture, specific gravity around 2.6-2.7.
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Physical properties
Hardness of 6.5-7 on the Mohs scale, colors ranging from dark grey to brownish-orange, dull to waxy luster, microcrystalline structure, conchoidal fracture, specific gravity around 2.6-2.7.
Formation & geological history
Formed through volcanic activity (basalt) combined with hydrothermal or secondary silica deposition (jasper) over millions of years, later weathered and rounded by river or wave action.
Uses & applications
Used primarily for decorative landscaping, ornamental carvings, lapidary work, and as a collector's specimen.
Geological facts
River tumbling naturally polishes and exposes the intricate color patterns created by iron oxide staining within the rock matrix.
Field identification & locations
Commonly found in stream beds, beaches, and glacial till; identifiable by its smooth, water-worn shape, multicolored banding or mottling, and resistance to scratching by steel.
