Chapter 11. The quantitative igneous rock classification

Extract from beginning of chapter:

AGITATION OVER THE STATE OF IGNEOUS ROCK CLASSIFICATION

The nomenclature of igneous rocks and their classification are subjects so intimately linked together that it is difficult to treat one without involving a discussion of the other. So it happened that in the agitation that arose during the 1890s over rock nomenclature, and found expression in the formation of an International Committee on the Nomenclature of Igneous Rocks, the question of classification became more and more prominent. The agitation culminated in the publication, in the Compte Rendu of the Eighth Session of the International Geological Congress in Paris in 1900 (Congrès Géologique International, 1901), of the Petrographical Lexicon, first published by Loewinson-Lessing (1894), and afterwards edited by himself and Barrois with the aid of an international committee of petrographers. The problem of classification took a course as surprising in its nature as it was unexpected in its method of solution. It was not international in its evolution, the proceedings of the committee on nomenclature demonstrating the hopelessness of attempting any constructive operations of an international character. As the sequel will show, it required the most intimate cooperation of closely affiliated colleagues at one on fundamental principles, and incidentally maintaining such amiable relations to one another as to be capable of sustaining considerable temperamental stress without undergoing permanent strain.

In a letter from Judd, concerning papers by Cross (1892) and myself (Iddings, 1892d) on spherulitic crystallization, already referred to in another connection, he wrote:¹

On the question of nomenclature, too, I find