English: Kimberlite from the Devonian of Russia.

This kimberlite sample is from an exploratory drill core in a diamondiferous pipe in northwestern Russia. The yellowish-green grains are serpentinized olivine with mesh texture.

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

Autolith kimberlite breccia, Arkhangelskaya Pipe, Zolotitskoye Field.

Breccia structure. Quantity of autoliths in rock reaches 20-50%. The size of the autoliths varies in wide limits from 0.1-1.5 to 4-5 millimeters and more. Ratio of large and small autoliths is changing on the background of usual predominance of small autoliths having size 0.5-1.0 millimeters over large ones. Cemented kimberlite mass has microporphyric structure. It contains up to 30-35% of microporphyric olivine having sizes 0.2-1.5 millimeters (as a rule replaced by serpentine-saponite aggregate) and 65-70% of matrix formed by coarse-grained serpophyte (serpentine) or saponite-serpophyte aggregate. In some areas of matrix rare flakes of changed phlogopite are noted. Among diamond-satellite minerals chrome spinellids (hundred grams/ton) and chrome-diopside (tens of grams/ton) predominate above garnet. Higher content of deep xenoliths (in comparison with other diatremes of provinces) is typical for autolith kimberlite breccia of Arkhangelskaya pipe.

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Geologic unit: Arkhangelskaya Pipe, Zolotitskoye Field, Late Devonian

Locality: Lomonosov Diamond Mine, north-northeast of the town of Arkhangelsk, Arkhangelsk Region, east of the White Sea, northwestern Russia (65° 17' 26.41" North latitude, 41° 01' 04.64" East longitude)