I shall begin somewhat bluntly by asking the question, “What is metasomatism ?”
Perhaps I am right in saying that there is a general impression abroad that metasomatism is a sort of replacement of one mineral by another, with addition of material and mainly of importance in ore deposits. I would like you to look at it from a far broader viewpoint—as a universal process based on the fact that the minerals of all rocks are soluble in the fluids of nature, particularly water, but also in the mixed emanations from magmas, and on the fact that these fluids change the minerals to others, of different composition, stable under the particular conditions of pressure and temperature prevailing. Remove metasomatism and there would be very little left of metamorphism.
I would define metasomatism as an essentially simultaneous, molecular process of solution and deposition by which, in the . . .