Barchinskii

This intrusion is situated to the southwest of the town of Kokchetav. It is 4.3 km long, but averages only 300-350 m in width, and is composed of pyroxenites, alkaline gabbroids, including olivine gabbro, malignite, sviatonossite, pulaskite and shonkinite, nepheline syenites and syenite porphyries, as well as carbonatites. The carbonatites generally form veined and lense-like bodies situated among pyroxenites and metasomatically altered ultrabasic and nepheline-bearing rocks. Apart from calcite the carbonatites contain magnetite, phlogopite, forsterite, feldspar, pyroxene (diopside, augite-diopside and aegirine-diopside) and up to 10% apatite. The accessories are spinel, magnetite, perovskite, baddeleyite and brown zircon.