mineral
Tumbled brown chalcedony/jasper
Microcrystalline quartz (SiO₂), likely iron-stained chalcedony or jasper
AI-generated identification · may be incorrectTypically Mohs hardness 6.5–7, opaque to weakly translucent, brown/tan with earthy iron-oxide staining, and a waxy to dull luster; lacks visible cleavage and has a cryptocrystalline quartz structure.
Identified More mineral →
Explore Tumbled brown chalcedony/jasper in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Typically Mohs hardness 6.5–7, opaque to weakly translucent, brown/tan with earthy iron-oxide staining, and a waxy to dull luster; lacks visible cleavage and has a cryptocrystalline quartz structure.
Formation & geological history
Forms when silica-rich groundwater fills cavities or fractures, later acquiring brown coloration from iron oxides; the specimen appears mechanically tumbled and polished rather than naturally weathered. Age cannot be determined from the image.
Uses & applications
Used as a lapidary material for cabochons, beads, carvings, and decorative stones; common pieces have modest collector value.
Geological facts
Jasper is opaque and commonly patterned, while chalcedony is more translucent; this specimen may represent an overlap or iron-stained chalcedony rather than a precisely identifiable variety.
Field identification & locations
Commonly found in volcanic terrains, sedimentary silica deposits, and gravel beds worldwide. A glassy or waxy surface, quartz-like hardness, and inability to scratch it with a steel knife support identification; acid does not react.
