English: Kimberlite from the Devonian of Russia.

This kimberlite sample is from an exploratory drill core in a diamondiferous pipe in northwestern Russia.

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Sample description by a Russian diamond exploration geologist (I'm not 100% sure who it was):

Kimberlite xenotufobreccia (kimberlite xenotuff breccia), Snegurochka Pipe, Zolotitskoye Field.

Crystallolithoclastic structure. Clastic material forms 90% of rock and is represented by clasts of kimberlites (25-35%) and their fragments (5-10%), fragments of enclosing rocks of argillites and aleurolites (30-20%), and also clastic quartz grains (20-25%). Among xenogenic material there are fragments of plagioclase and K-feldspar, large fragments of chloritized mica. In xenotufobreccia of Snegurochka Pipe, xenoliths of metamorphic rocks of crustal basement (amphibolites, biotite schists, plagioclase granites, granite gneisses) are presented more often. Cement of xenotufobreccia (basal or interstitial) forms up to 10% and fills small interstices between fragments. It is represented by pelitomorphic material with hydrous ferric oxides, carbonate, hydromica, and saponite. Fragments of kimberlites consist of saponite pseudomorphs of rounded phenocrysts of olivine of the first generation, subidiomorphic phenocrysts of olivine of the second generation, and saponite matrix with the hydromica and carbonate admixtures. Fragments have irregular forms with smoothed angles, and often have traces of magmatic resorption complicating contours of grains. Carbonate (3%) is present in the forms of small grains in breccia cement and in matrix of kimberlite fragments, in the form of veins in argillite fragments and films around the grains of quartz.

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Geologic unit: Snegurochka Pipe, Zolotitskoye Field, Arkhangelskaya Diamond Province, Late Devonian

Locality: Snegurochka Pipe, north-northeast of the town of Arkhangelsk, Arkhangelsk Region, east of the White Sea, northwestern Russia