fossil

Fossil Coral

Hexagonaria (agatized coral)

Hardness of 6.5-7 on Mohs scale, grayish-white to tan color, waxy to vitreous luster, microcrystalline quartz structure.

Identified November 7, 2026More fossil →

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Physical properties

Hardness of 6.5-7 on Mohs scale, grayish-white to tan color, waxy to vitreous luster, microcrystalline quartz structure.

Formed in ancient shallow marine environments when silica-rich groundwater replaced the original coral skeleton structure over millions of years.

Used primarily in lapidary arts, wire-wrapped jewelry, and by fossil or mineral collectors.

Fossil coral often preserves intricate details of the ancient coral polyps that lived during the Paleozoic era.

Identify by distinctive honeycomb or star-shaped cellular patterns on the surface; commonly found in limestone-rich regions worldwide.

Probable fossil-bearing rock or mineral concretion

Unidentified carbonate-rich concretion with a possible fossil inclusion

Likely fossil oyster shell

Fossilized bivalve shell; exact species cannot be identified from the image

Crinoid Stem Fossil in Matrix

Phylum Echinodermata, Class Crinoidea

Fossiliferous limestone (likely a crinoidal or shell-fragment limestone)

Bioclastic limestone, composed chiefly of calcite (CaCO₃)

Porous limestone pebble

Calcite-rich limestone (primarily CaCO₃); exact identification is uncertain from the image

Fossil oyster shell

Oyster (family Ostreidae); shell composed chiefly of calcite (CaCO₃)