Chinskii

This alkaline massif, extending over 7.5 x 3.2 km, intrudes Lower Cambrian terrigenous carbonate sediments and lower Palaeozoic granitoids. The intrusion is composed mainly of peralkaline syenites but in the central part are some patches of nepheline syenite that occupy a total area of about 0.5 km2. The composition of the peralkaline syenites is microcline-perthite, plagioclase, aegirine-augite, titanian garnet (up to 10%) and corundum with occasional quartz. Titanite, apatite, fluorite and Fe-Ti oxides are accessory. The nepheline syenites are medium- to coarse-grained massive rocks consisting of microcline (5-10%), microcline-perthite (55-60%), nepheline (20%), aegirine (10%), garnet (10%), biotite (3%), apatite, rutile, and Fe-Ti oxides. Analyses of the rocks will be found in Andre’E v et al. (1969).