sedimentary
Jasper and Mixed River Pebbles
Microcrystalline Quartz (Chalcedony / Jasper)
AI-generated identification · may be incorrectHardness: 6.5 to 7 on the Mohs scale. Colors vary widely including yellow, brown, red, and dark gray due to various mineral impurities. Luster is typically waxy to dull. Crystal structure is microcrystalline (trigonal). Cleavage is absent (fractures conchoidally). Specific gravity ranges from 2.58 to 2.91.
- Hardness
- 6
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Physical properties
Hardness: 6.5 to 7 on the Mohs scale. Colors vary widely including yellow, brown, red, and dark gray due to various mineral impurities. Luster is typically waxy to dull. Crystal structure is microcrystalline (trigonal). Cleavage is absent (fractures conchoidally). Specific gravity ranges from 2.58 to 2.91.
Formation & geological history
Formed through the deposition and lithification of silica-rich sediments or the alteration of existing rocks by silica-rich hydrothermal fluids over millions of years.
Uses & applications
Used primarily in lapidary arts, ornamental carvings, polished stones, and as decorative gravel or landscaping stones.
Geological facts
Jasper has been used since ancient times for amulets, seals, and jewelry. The variety of colors comes from iron oxides and other mineral inclusions trapped during formation.
Field identification & locations
Commonly found in river beds, beaches, and glacial till where durable stones have been weathered and rounded by water transport over long distances.
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