Rock Identifier
Tumbled brown agate or jasper (Microcrystalline quartz, SiO₂, likely chalcedony with iron-oxide inclusions) — mineral
mineral

Tumbled brown agate or jasper

Microcrystalline quartz, SiO₂, likely chalcedony with iron-oxide inclusions

AI-generated identification · may be incorrect

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.

Identified More mineral →
Explore Tumbled brown agate or jasper in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

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.