mineral
Tumbled jasper or chert
Microcrystalline quartz (SiO₂), likely opaque chalcedony/jasper
AI-generated identification · may be incorrectSmooth, rounded, polished surface; mottled brown, olive-green, gray, and cream colors with a waxy to vitreous luster. Hardness is approximately 6.5–7 Mohs; no visible cleavage; specific gravity about 2.6.
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Physical properties
Smooth, rounded, polished surface; mottled brown, olive-green, gray, and cream colors with a waxy to vitreous luster. Hardness is approximately 6.5–7 Mohs; no visible cleavage; specific gravity about 2.6.
Formation & geological history
Forms when silica-rich fluids fill cavities or replace sedimentary material, commonly producing microcrystalline quartz with iron-oxide and clay inclusions. The specimen has been human-tumbled and polished; its precise geological age and source cannot be determined from the image.
Uses & applications
Used as an inexpensive ornamental stone, bead, cabochon, worry stone, and lapidary material; occasionally used decoratively in mosaics and small carvings.
Geological facts
Jasper is an opaque variety of chalcedony, while chert is a closely related microcrystalline quartz rock; color zoning and translucency can overlap between them.
Field identification & locations
Identify by its glassy/waxy polish, very high hardness, and resistance to scratching by a steel knife; it should not fizz in dilute hydrochloric acid. Common sources include the western United States, Mexico, Brazil, India, and Australia.
