The Tibbit Hill Formation is a group of metamorphosed volcanic rocks located in the Waterloo area of Quebec, Canada. The formation is predominantly metabasaltic, with these rocks enclosing a band of metafelsites 15 x 2.5 km. Protolith volcanics relate to the opening of the Iapetus Ocean, later metamorphosed to greenschist facies during the formation of the Appalachian foldbelt in which they reside. As a result, the primary igneous mineralogy has been wholly replaced, converting metafelsites to muscovite-quartz-albite schists. The mineralogy is consistent with rhyolitic compositions, with HFSE and REE chemistry suggesting the protoliths were peralkaline and comenditic. Agpaitic indices are <1, however this is explained by the loss of alkalis during metamorphism. Detailed major and trace element analysis can be found in Kumarapeli et al. (1989).