Petrified Slice of Colla Wood

Colla wood is a rare type of petrified wood found only near the Black Sea town of Zile, Turkey. Having fossilized over an active copper deposit, copper-bearing minerals such as azurite, malachite, and chrysocolla (hence the name "colla wood") absorbed into the wood, slowly replacing the original organic material and creating vibrant streaks of blue and green. Other minerals — such as chalcedony and hematite — produce red, brown, and white accents in colla wood, as can be seen in the specimen offered here.