mineral
Tumbled yellow jasper or chalcedony
Microcrystalline quartz, SiO₂; likely iron-oxide-bearing jasper/chalcedony
AI-generated identification · may be incorrectHardness about 6.5–7 Mohs; opaque to slightly translucent, mustard-yellow to honey-brown, with a smooth polished surface and vitreous-to-waxy luster. Quartz has a trigonal crystal structure, but this specimen is microcrystalline and shows no visible cleavage.
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Physical properties
Hardness about 6.5–7 Mohs; opaque to slightly translucent, mustard-yellow to honey-brown, with a smooth polished surface and vitreous-to-waxy luster. Quartz has a trigonal crystal structure, but this specimen is microcrystalline and shows no visible cleavage.
Formation & geological history
Forms when silica-rich fluids fill cavities or replace older rock, with iron oxides producing the yellow-brown color; age depends on its source deposit. The rounded shape is human-made by tumbling and polishing.
Uses & applications
Used as an inexpensive ornamental stone, cabochon, bead, and decorative object; not typically used in construction. Common tumbled pieces usually have modest collector value.
Geological facts
Jasper is an opaque variety of chalcedony, while more translucent material may be classified as yellow chalcedony or silicified rock. Color zoning and iron staining are common.
Field identification & locations
Identify by its glassy/waxy polish, lack of cleavage, fine-grained texture, and ability to scratch glass; a steel blade should not scratch it easily. Common sources include Brazil, Madagascar, India, Uruguay, and the western United States.
