Drazhilovskoye W-Mo deposit, Kostanay Region, Kazakhstan
Thin veins and veinlets of emerald-bearing phlogopite glimmerites occuring in lenticular interbeds of carbonate-talc rocks with thickness of 5 to 50 m, which are part of a complexly deformed Upper Proterozoic amphibole-quartzite-schist sequence.The phlogopite glimmerites generally have a fringe of late white talc and rarely contain semitransparent small emeralds, up to 1 cm in size.
Ref: E. Ya. Kievlenko, Geology of gems, 2003, p. 84