Bancroft area (Bancroft district), Ontario, Canada
Sapphire-bearing pegmatites without nepheline. Crystals of corundum are up to 1.5 x 5 cm in size, grayish blue colour, locally transparent and are associated with microcline, titanite, biotite. Some crystals are partially cuttable.
Ref: E.Ya. Kievlenko (2003) Geology of gems, p. 49