Mavragubskii

Mavragubskii is located on the northern bank of Lake Verhnyaya Pirenga, near the mouth of the Mavra River. It is a small intrusion of 0.5x1.5 km consisting of melteigite and ijolite. The central part is unexposed but geophysical data indicate that it probably consists of melanocratic, highly magnetic rocks such as clinopyroxenite or other ultramafic types. The melteigites and ijolites are texturally and structurally highly variable grading from massive to banded and through coarse-, medium-, fine-grained and porphyritic varieties. The rocks comprise pyroxene, varying from diopside to aegirine (35-60%), nepheline (30-50%), titanite (2-8%), phlogopite (3-8%), apatite (0.5-5%) and olivine (1-3%) with accessory magnetite, sulphides, K-feldspar, cancrinite, calcite, sodalite and liebenerite. The country rock granite gneisses are fenitized, the width of the aureole varying between 1 and 1.5 km. Malignites have been formed in the inner aureole.