The Rarer Metallic Constituents of Some American Igneous Rocks. I

Abstract

This paper presents a study of the abundance and distribution of some of the rarer metallic constituents in igneous rocks. By means of chemical trace methods, 354 determinations have been made of metals, including molybdenum, beryllium, lead, zinc, cadmium, copper, nickel, and cobalt. The samples represent six regions: (1) the Michigan copper district, (2) Minnesota, (3) the St. Francois Mountains, Missouri, (4) the Llano uplift of central Texas, (5) the Clear Lake area, California, and (6) two New England localities. The distribution of the minor elements is influenced by the major chemical constituents to a very appreciable extent. Apparently this is chiefly the result of isomorphous replacement of the major elements by the minor constituents in rock-forming minerals in accordance with the principles outlined by V. M. Gold-schmidt. A number of relationships between minor and major constituents are indicated, although some are purely tentative. Geologic factors are of great importance in determining th...