Artem

In the Artem depression, in the vicinity of the city of Artem, lavas and sills of trachydolerite, shoshonitic absarokite and leucite and pseudoleucite shoshonitic absarokites are widespread. They also form dykes, stocks of up to 4 km2 and laccoliths. One of the laccoliths is formed by fergusites which are dark grey to black, porphyritic rocks with phenocrysts of biotite, sanidine, anorthoclase, pseudoleucite, a small amount of olivine and clinopyroxene of variable composition (diopside, aegirine-augite). Calcite is present in the fine-grained matrix and apatite is a usual accessory.