In 19072 I presented the “Zonal Theory” of ore deposition in a paper, the conclusion of which was as follows:
“Summing up, this theory proposes that metalliferous fluids, from which most ore deposits are precipitated, are extreme differentiation phases of rock magmas; that most ore deposits and ‘mineral veins,’ as a class, represent one or the other of the extreme products of magmatic differentiation; and that the most striking chemical differences between ore deposits is due (in the more important class representing the siliceous extreme) to successive precipitation in theoretically vertical zones, as the fluid migrates toward the surface, and with diminishing heat achieves more and more mature crystallization.”
I defined the principal zones as: 1, the pegmatite zone, containing tin, tungsten, molybdenum, etcetera; 2, the gold quartz-auriferous pyrite zone; 3, the copper zone; 4, the lead-zinc zone; 5, the silver zone with much gold; . . .