Nisikkatch Lake

A series of apatite and carbonate-rich veins occurs in an area of about 1x10 km extending from Nisikkatch Lake northeastwards to Lane Lake (Hogarth, 1957, Fig. 1). (Some 50 km further along the strike to the northeast lies the Thomas Lake occurrence - 031-00-008). The veins are up to 3 m thick and the longest observed is about 30 m. They are zoned with variable inner zones of carbonate, apatite, feldspar and pegmatite, and an invariable marginal zone of amphibolite. All the occurrences are radioactive due to the presence of thorium minerals in the apatite zone. The apatite is also particularly rich in REE. The carbonate zone consists essentially of calcite, with about 30% quartz, 9.6% baryte, 5.9% apatite, chlorite and allanite; analcime, gypsum, pyrite, siderite, zircon and sphene were also identified. The feldspar zone consists essentially of hyalophane with a little microcline and albite, and in two veins a late arfvedsonitic amphibole occurs forming a third of the rock in one of them. The pegmatitic zone is only found in the northeastern part of the area and consists of perthite, albite, scapolite, quartz and amphibole. The vein system may have carbonatitic affinities, as suggested by Currie (1976a, p. 171).