English: Volkonskoite-replaced fossil wood from the Permian of Russia. (4.2 cm across at its widest)

This is a very rare specimen of fossil wood from Permian rocks in western Russia. Most fossil wood is preserved by quartz-permineralization or carbonization. This fossil wood has been replaced by a rare chromian smectite clay mineral called volkonskoite (Ca0.3(Cr,Mg,Fe)2(Si,Al)4O10 (OH)2⋅4H2O - hydrous calcium chromium magnesium iron hydroxy-aluminosilicate). The chromium (Cr) content gives the fossil its green coloration. The striations appear to be remnants of the original wood structure. The broken sides show that the massive, fine-grained volkonskoite breaks with a conchoidal fracture.

Host rocks & age: soft fluvial sandstones, Kazanian to Tatarian Stages, upper Upper Permian

Locality: Mt. Efimiatsk (Mt. Efimyatskaya), near the town of Efimyata, ~10 miles west of Votinsk Reservoir & ~30 miles southwest of Okhansk, Chastinsky District, southwestern Perm Region, western foothills of the southwestern Ural Mountains, western Russia