mineral
Tumbled brown chalcedony or jasper
Microcrystalline quartz (SiO₂), likely iron-stained chalcedony/jasper
AI-generated identification · may be incorrectHardness 6.5–7 Mohs; brown to honey-gray, opaque to slightly translucent, with a waxy to dull luster. It lacks visible crystal faces and shows conchoidal fracture; the rounded shape indicates tumbling or natural abrasion.
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Physical properties
Hardness 6.5–7 Mohs; brown to honey-gray, opaque to slightly translucent, with a waxy to dull luster. It lacks visible crystal faces and shows conchoidal fracture; the rounded shape indicates tumbling or natural abrasion.
Formation & geological history
Forms when silica-rich fluids fill cavities or fractures, later colored brown by iron oxides; jasper is opaque, while chalcedony is more translucent. Such material commonly formed in volcanic terrains during the Cenozoic or older geologic periods.
Uses & applications
Used for inexpensive cabochons, beads, carvings, tumbling, and decorative objects; generally low commercial value.
Geological facts
The image does not permit confident separation of jasper from iron-stained chalcedony; a light-transmission test and close examination of banding would help.
Field identification & locations
Common sources include Brazil, Madagascar, India, Uruguay, Mexico, and the western United States. Identify it by its glass-scratching hardness, lack of cleavage, waxy surface, and absence of metallic sparkle; avoid confusing it with dyed glass or slag.
