Vivianite in Fossil Clam Shell

This specimen showcases radiating tufts of black vivianite blades on a layer of hydrogoethite over a limonite matrix. Although the vivianite crystals appear black, they reveal a subtle blue hue under strong backlighting. The unique setting for these vivianite crystals is the fossilized interior of a mollusk shell, partially replaced and filled with the dark crystalline mineralization.

Originating from the Kerch Peninsula near the Black Sea in Ukraine, these remarkable specimens are a true mineralogical rarity. The calcium and phosphate required for vivianite’s formation come directly from the original shell material, making these pieces a blend of mineral specimen, fossil, and pseudomorph all in one. Since the vivianite deposit is now depleted, these shell specimens have become classics and are highly valued by collectors.

The shell has likely been reattached, as a small amount of adhesive is visible in a couple of spots around the perimeter. Nevertheless, these striking specimens are among the most famous examples of fossil/mineral replacements, combining geological and paleontological significance.