Rock Identifier
Polished fossil coral pendant (Agatized or silicified colonial coral; commonly sold as fossil coral jasper) — fossil
fossil

Polished fossil coral pendant

Agatized or silicified colonial coral; commonly sold as fossil coral jasper

AI-generated identification · may be incorrect

Cream, tan, and brown mottled pattern with fossil-like corallite shapes; opaque to slightly translucent, waxy-to-glassy luster, Mohs hardness about 6.5–7 if silicified. The pictured piece is polished and mounted as jewelry; crystal structure is microcrystalline quartz.

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Physical properties

Cream, tan, and brown mottled pattern with fossil-like corallite shapes; opaque to slightly translucent, waxy-to-glassy luster, Mohs hardness about 6.5–7 if silicified. The pictured piece is polished and mounted as jewelry; crystal structure is microcrystalline quartz.

Formation & geological history

Formed when ancient coral was buried and its skeletal material was replaced or filled by silica during fossilization. Fossil coral occurs in sedimentary strata of varied ages, depending on the deposit.

Uses & applications

Used for pendants, beads, cabochons, and decorative objects; the specimen shown has been shaped and polished for jewelry.

Geological facts

Silicified fossil coral preserves the coral colony’s distinctive small cells, or corallites, as contrasting patterns.

Field identification & locations

Look for repeated cellular or flower-like structures rather than random mineral banding; common sources include Indonesia, Madagascar, and the United States. Similar-looking patterned jasper may not be fossil coral, so identification from appearance alone is uncertain.

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