Venturi Township (Township 107, Spanish River)

A body of carbonatite at least 1.2 km long and 200 m wide strikes northeast and dips to the southeast, but its full extent is obscured by swamp and drift, although it certainly extends into Township 108 to the north. The body cuts Precambrian granite gneisses and is itself dissected by mafic dykes. The carbonatite is dolomitic, strongly foliated, and brecciated with abundant phlogopite. Vermiculite is present and apparently formed by the alteration of the dykes. An extensive fenite aureole including sodic amphibole-rich types has been detected by drilling (J.Gittins, personal communication and P. Mainwaring - quoted in Currie, 1976a, p. 132).