Large skarn corundum deposit.
Archean metamorphic rocks of the Highland group are developed in this region. The skarns are in the axial part of a large anticline near the base of a sequence of calcite-dolomitic marbles, which are underlain by quartz-syenite migmatites and overlain by charnockites, quartzites and biotite-garnet gneisses. The ovoid skarn body is 35 m long, maximum 12 m thick, and cuts across the axis of the fold.
The generation of transparent corundum is represented by greenish light blue and blue sapphire
in prismatic and acute-pyramidal crystals, up to 1 cm long. Similar sapphires are found in placer deposits in this region.
Ref: E.Ya. Kievlenko, Geology of gems, 2003, p. 56