metamorphic
Tumbled yellow quartz-rich stone, likely yellow jasper or quartzite
Jasper/quartzite; mainly microcrystalline quartz (SiO₂), with iron-oxide staining
AI-generated identification · may be incorrectOpaque cream-to-yellow-brown, fine-grained, matte to weakly waxy luster, with no visible cleavage; quartz hardness is about 7 Mohs, though the exact specimen may vary. Its rounded shape indicates tumbling or natural abrasion.
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Physical properties
Opaque cream-to-yellow-brown, fine-grained, matte to weakly waxy luster, with no visible cleavage; quartz hardness is about 7 Mohs, though the exact specimen may vary. Its rounded shape indicates tumbling or natural abrasion.
Formation & geological history
Likely formed from silica-rich sediment or altered rock, with iron minerals producing the yellow coloration; the geological age cannot be determined from the photograph. Yellow jasper commonly forms in volcanic or sedimentary settings, while quartzite forms by metamorphism of sandstone.
Uses & applications
Used as a lapidary stone for beads, cabochons, carvings, and decorative pieces; commercial value is generally modest.
Geological facts
The specimen is not diagnostic enough visually to distinguish jasper from stained quartzite or massive quartz. A white streak, strong glassy fracture, and scratch resistance near Mohs 7 support quartz content.
Field identification & locations
Commonly found in silica-rich gravels and quartz-bearing regions worldwide, including Brazil, India, Madagascar, and the western United States. Field identification requires a fresh surface, streak test, hardness test, and ideally mineralogical analysis.
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