Leonard James Spencer, 1911 Encyclopædia Britannica, Volume 21… (1911)
“ In Canada it occurs with apatite in pyroxene rocks which are intrusive in Laurentian gneisses and crystalline limestones, the principal mining district being in Ottawa county in Quebec and near Burgess in Lanark county, Ontario. In Ceylon, the mineral forms irregular veins, rarely exceeding one or two feet in width, traversing granulate, especially near the coptact of this rock with crystalline limestone. ”
