Elisenvaarskii (Kaivimyaki And Raivimyaki)

Two areas of outcrop of alkaline gabbroic rocks and syenites, called Kaivimyaki and Raivimyaki, which are surrounded by fenites, appear to represent parts of a single, larger occurrence with an area of about 30 km2. They are located within the approximately north-south-trending deep-seated fracture zone of Western Preladoga. Here in an area 20 km long and about 5 km wide occur outcrops of alkaline gabbroids and syenites, as well as related fenites, the last consisting of albite, microcline, phlogopite, hastingsite and apatite. The alkaline gabbroids are the most abundant rocks. Peralkaline syenites and melasyenites consist of orthoclase-perthite, aegirine-diopside and hastingsite with enrichment of apatite in places. Among the peralkaline syenites Khazov (1982) has described melanocratic varieties containing 1-20% of aegirine-diopside, 1-50% of hornblende, 5-45% biotite, along with orthoclase-perthite (20-70%) and apatite (2-8 to 15-20%). The apatite-rich varieties of these rocks have been called nevoite and ladogalite by Khazov (1982 and 1983). The rocks described above are intersected by dykes of syenite pegmatite, syenite aplite and alkaline lamprophyres, the last forming eruptive breccias. There is some apatite mineralisation associated with these massifs.