mineral
Tumbled yellow chalcedony (likely yellow jasper)
Microcrystalline quartz, SiO₂; chalcedony/jasper variety
AI-generated identification · may be incorrectSmooth, rounded, mustard-yellow to honey-brown, with a waxy-to-glassy luster and no visible cleavage; Mohs hardness about 6.5–7, specific gravity approximately 2.6. The opaque appearance suggests jasper, while translucency at the edges may indicate chalcedony.
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Physical properties
Smooth, rounded, mustard-yellow to honey-brown, with a waxy-to-glassy luster and no visible cleavage; Mohs hardness about 6.5–7, specific gravity approximately 2.6. The opaque appearance suggests jasper, while translucency at the edges may indicate chalcedony.
Formation & geological history
Forms when silica-rich groundwater fills cavities or fractures, precipitating microcrystalline quartz; iron oxides commonly create the yellow-brown color. Deposits range from Precambrian to recent, depending on locality.
Uses & applications
Used as a tumbled decorative stone, cabochon, bead, or paperweight; attractive pieces have modest lapidary value.
Geological facts
Jasper and chalcedony are varieties of quartz distinguished mainly by texture and opacity rather than chemical composition. Yellow coloration commonly reflects limonite or goethite inclusions.
Field identification & locations
Identify by its very hard, glass-scratching surface, smooth conchoidal fracture, waxy luster, and lack of cleavage; it is commonly found in volcanic cavities, sedimentary silica deposits, and river gravels.
