The Nemag Lake fenite occurrence covers about 800x600 m and lies 5 km northeast of the Kusk Lake occurrence (No. 78). As at Kusk Lake Mississagi Quartzite, consisting essentially of feldspathic sandstones and greywackes, has been fenitized with the development of veining and brecciation, and growth of secondary aegirine, alkali amphibole, alkali feldspar and some late biotite. Several stages of increasing fenitization have been mapped from shattering of the rocks with little mineralogical change through stages of veining and intensive metasomatism, often with the spectacular marginal replacement of angular quartzite blocks (Siemiatkowska and Martin, 1975, Fig. 1_4). There are late quartz veins and a single 1.5x0.6 m ankerite vein is the only carbonate to have been found in the fenites. Igneous rocks are not present. Rock analyses are available, as are microprobe analyses of aegirine, alkali amphibole, alkali feldspar, Nb-rutile and opaque phases.