Other Names: International
District: Mirny kimberlite field
Commodities :   Diamond

Major diamond deposits are exploited over the north-esatern section of the largely concealed Yakutia Archaean Craton, which is exposed through younger Siberian Platform cover as the Anabar and Aldan Shields to the north and south respectively, in eastern Siberia. There ar etwo groups of kimberlites, namely the diamondiferous varieties which are over Archaean-Proterozic basement and non-diamondiferous, younger, pipes on the margins of the platform. The diamondiferous pipes are found cutting platformal sequences overlying a crystalline basement which is at a depth of around 4 km, which decreases to the north. 

A series of diamond mining divisions of Almazy Rossii-Sakha Joint Stock Co. Ltd. (ALROSA), exploit both kimberlite and alluvial deposits in the Yakutia region, in the Sakha Republic in Siberia, as follows: 

Mirny Division in the Malaya - Botuobiya (or Mirny) Field, which comprises the mines on the now exhausted Mir pipe and the Dachnaya and Internationalnaya pipes. The grade at Mir varied from as high as 400 carats per hundred tonnes (cpht) to as low as 0.05 cpht, but averaged approximately 60 cpht of which around 25% were gem quality. Mir was the first of the main Siberian mines. The pipe was discovered in early 1955 and had a diameter of approximately 800 m and covered and area of some 7 ha. It had an oval shape at surface and comprised a funnel shaped pipe that dipped at 75 to 90° intruding Ordovician limestones. There are a variety of kimberlite types characterised by different quantities of xenoliths of country rock, which decrease with depth. Crystalline schist and deep seated xenoliths are rare. Eclogites are subordinate to pyrope bearing ultramafics (lherzolites accompanied by websterites and harzburgites predominating). The Internationalnaya (or International) pipe is small but very high grade.

Aikhal Division in the Alakit Field, which includes the Aikhal, Jubileynaya and Sytykanskaya kimberlite deposits. This field is some 450 km north to NNW of Mirny. The Jubileynaya (or Jubilee) pipe is large by Siberian standards and is to be mined by open cut. 

Udachny Division in the Daldyn Field which includes the Udachny operation and the Zarnista, Yakutskaya, Leningradskaya and Dalnaya pipes. This field is immediately to the north-east of, and overlapts with the Alakit Field. The kimberlites of the Alakit and Daldyn fields have been dated at 345 and 390 Ma (Devonian to lower Carboniferous).   The Udachny (or Udachnaya) pipe was discovered in 1955 and comprises two adjacent pipes the Udachnaya East and Udachnaya West, composed respectively of massive kimberlite with fresh olivine, and kimberlite breccia with more abundant xenoliths of mainly crystalline schists, including plagioclase bearing eclogite rich rocks. Both pipes contain xenoliths xenoliths of pseudo-porphyritic, pyrope peridotite. The country rock is lower Ordovician limestones. In 1999 Udachny and Zarnista accounted for around 80% of Russian diamond production. 

Anabar Division which exploits alluvial/placer diamond deposits in an area some 300 to 400 km to the north to NNW of the Alakit Field. Kimberlite pipes within the Anabar division have been dated at between 195 and 245 Ma (early Triassic to early Jurassic). 

Nyurba Division which includes the new Nakynskoye ore field and the Nyurbinsk and Botuobinskaya (or Botubinsk) pipes which are 300 km north-east of Mirny and 300 km south-east of Aikhal. 

There are over 1000 known kimberlite pipes and dykes on the Siberian Platform in 20 fields, with at least 150 containing diamonds, although only those listed above have been, or are planed to be mined in the four kimberlite fields and one alluvial district. 

The annual production capacity is 12 million carats. The actual company's production was valued at USD1.623 billion in 2000. Russian production in 1999 (almost 100% Alrosa) amounted to around 11.5 million carats of each of gem and industrial diamonds. 

DM Sample Photographs