The Geology of Parts of Lots 11 and 12, Range IX, Calumet Island, Quebec
Lots 11 and 12, Range IX, Calumet island, are underlain by a Grenville metamorphic complex into which sills of tourmaline granite pegmatite have been injected. The pegmatite has an average mode-potash feldspar 65 per cent, sodic plagicclase 10 to 20 per cent, quartz 5 to 20 per cent, tourmaline 10 to 15 per cent, accessory minerals < 5 per cent; it is unzoned except for a narrow border zone. Some of the feldspar has been replaced by calcite. Microcline has been •partially replaced by sodic plagioclase. Three varieties of tourmaline are present (black, blue, and green) and spectrographic analysis suggests progressive compositional changes during its crystallization.