sedimentary

Breccia (likely quartz-cemented polymict breccia)

Clastic breccia; chiefly angular quartz/feldspar or carbonate clasts in a silica- or carbonate-rich matrix

AI-generated identification · may be incorrect

Coarse, angular pale clasts in a tan-brown matrix; generally dull to slightly granular luster and no consistent cleavage. Hardness is approximately 5–7 depending on clasts and cement; density commonly 2.4–2.7 g/cm³.

Identified August 22, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms when broken rock fragments accumulate rapidly near faults, volcanic settings, or steep slopes and are later compacted and cemented. Age cannot be determined from the photograph; breccias occur from Precambrian to modern deposits.

Uses & applications

Used as decorative stone, polished cabochons, countertops, and architectural facing; unusual specimens are collected. Value is typically $5–$30 as a palm-sized polished or natural specimen, with exceptional lapidary pieces higher.

Geological facts

The defining feature is angular rather than rounded fragments, distinguishing breccia from conglomerate. The specimen appears shaped or polished, so surface appearance may obscure its original texture.

Field identification & locations

Look for sharp-edged clasts, contrasting colors, and visible cement; a vinegar test can suggest carbonate cement, while glassy grains and strong scratching ability suggest quartz. Common worldwide in fault zones, alluvial fans, impact structures, and volcanic terrains.