mineral
Tumbled brown agate or jasper
Microcrystalline quartz, SiO₂, likely chalcedony with iron-oxide inclusions
AI-generated identification · may be incorrectHardness about 6.5–7 Mohs; rounded, polished pebble with brown, honey, and cream coloration, waxy to vitreous luster, and no visible cleavage. The granular pale area may be quartz or weathered host material; exact identification requires testing.
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Physical properties
Hardness about 6.5–7 Mohs; rounded, polished pebble with brown, honey, and cream coloration, waxy to vitreous luster, and no visible cleavage. The granular pale area may be quartz or weathered host material; exact identification requires testing.
Formation & geological history
Forms when silica-rich groundwater fills cavities and fractures in volcanic rock, with iron oxides producing the brown colors; commonly Cenozoic to older, depending on its source deposit.
Uses & applications
Used for cabochons, beads, carvings, tumbled stones, paperweights, and ornamental objects; attractive pieces have modest jewelry and collecting value.
Geological facts
Agate and jasper are varieties of chalcedony distinguished mainly by appearance: agate commonly shows banding, while jasper is more opaque and opaque-mottled. This specimen appears human-tumbled and may be a mixed or brecciated material.
Field identification & locations
Look for hardness sufficient to scratch glass, a smooth waxy surface, and conchoidal fracture; it should not fizz in dilute acid. Common sources include Brazil, Uruguay, Madagascar, India, Mexico, and the western United States.
