The Rockville granite of Minnesota is an unusually coarse-grained rock with abundant microcline phenocrysts and very little secondary alteration. In it late magmatic or deuteric effects are pronounced and, because of the coarse texture, relatively easy to study. The granite has been subjected to no recognized metamorphism beyond such deuteric replacement as occurred in direct continuation of primary crystallization. Therefore the phenomena described here are apparently uncomplicated by forces beyond those within astatic body of cooling magma. The granite is an excellent subject for a paragenetic analysis of normal crystallization in a rock of simple history.