mineral
Tumbled jasper or chert
Microcrystalline quartz (SiO₂), likely jasper/chalcedony
AI-generated identification · may be incorrectHardness about 6.5–7 Mohs; opaque tan, ochre, cream, and reddish-brown mottling with a waxy to dull luster and no visible cleavage. The rounded shape and smooth surface indicate natural water wear or tumbling.
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Physical properties
Hardness about 6.5–7 Mohs; opaque tan, ochre, cream, and reddish-brown mottling with a waxy to dull luster and no visible cleavage. The rounded shape and smooth surface indicate natural water wear or tumbling.
Formation & geological history
Silica-rich groundwater replaced or cemented sediment, forming microcrystalline quartz in cavities or beds; the specimen’s exact geological age cannot be determined from the image. Jasper commonly forms in volcanic or sedimentary environments.
Uses & applications
Used as ornamental stone, cabochons, beads, carvings, and decorative tumbled material; generally not used structurally.
Geological facts
Jasper is an opaque variety of chalcedony, while chert is the broader rock term for dense microcrystalline quartz. Color commonly comes from iron oxides and other trace minerals.
Field identification & locations
Identify by its opaque, fine-grained appearance, glassy-to-waxy fracture, lack of cleavage, and ability to scratch ordinary glass. Common sources include the western United States, Mexico, Brazil, Madagascar, and Australia.
