Kobarzinskii

At Kobarzinskii peralkaline and feldspathoidal syenites cut volcanic and sedimentary sequences including limestones of Cambrian age. The peralkaline syenites consist of alkali feldspar (57-69%) with biotite (up to 6%) and magnetite; there has been extensive replacement by muscovite which may form as much as 32% of the rock. Nepheline syenite has been observed in alluvial blocks and consists of microcline perthite (44-59%), nepheline (17-43%), aegirine-augite (up to 7%), biotite (up to 8%), sodalite, cancrinite, muscovite and minor apatite and titanite. Feldspathoid syenite contains very little nepheline and clinopyroxene, but is enriched in cancrinite and sodalite.