Whose classification of igneous rocks introduced the idea of fractional crystallization?

Norman L. Bowen, a Canadian-American petrologist, developed this concept in the early 20th century while studying how magma cools and solidifies. His Bowen reaction series, published in 1928, explains why certain minerals form first at high temperatures and others later as the melt cools. The idea of fractional crystallization became central to modern igneous petrology because it helps explain the chemical evolution of basalt, andesite, and granite. Bowen’s work remains one of the foundations of geology.