mineral
Tumbled yellow chalcedony (likely yellow jasper or quartz)
Microcrystalline quartz, SiO₂; probable chalcedony/jasper variety
AI-generated identification · may be incorrectPale yellow, opaque to slightly translucent, waxy to vitreous luster, and smoothly tumbled with no visible cleavage; quartz hardness is Mohs 7 and specific gravity about 2.6. The photograph cannot confirm exact mineral identity, and it may also be dyed or coated.
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Physical properties
Pale yellow, opaque to slightly translucent, waxy to vitreous luster, and smoothly tumbled with no visible cleavage; quartz hardness is Mohs 7 and specific gravity about 2.6. The photograph cannot confirm exact mineral identity, and it may also be dyed or coated.
Formation & geological history
Forms when silica-rich groundwater fills cavities, fractures, or sedimentary pores, later hardening into microcrystalline quartz; deposits range from ancient to recent. Yellow color commonly comes from iron staining or dispersed inclusions.
Uses & applications
Used for cabochons, beads, carvings, tumbling, and ornamental objects; jasper and common chalcedony have modest commercial value.
Geological facts
Chalcedony is fibrous cryptocrystalline quartz, while jasper is its opaque, impurity-rich form. A glassy fracture and lack of cleavage distinguish quartz varieties from many yellow feldspars.
Field identification & locations
Common in Brazil, Uruguay, Madagascar, India, Namibia, and the United States. A steel file should not easily scratch it; strong translucency suggests chalcedony, while complete opacity and mottling suggest jasper.
