The control of impounding structures on ore deposition

Abstract

Various structures have been described from time to time as super-imposed strata, blankets, traps, dams, inverted ponds and ponds. It is the theme of this paper that the relatively impermeable barriers that are common to these structures impounded the solutions in such a manner as to cause the metals to be deposited within the structure and to allow the solvent or ore carrying fluid to pass on through the relatively impermeable barrier.It is shown that some elements require a more perfect barrier than others to impede their progress and these differences are reconciled with the general position of the metals in the hydrothermal series. The phenomenon responsible for this impedance is held to be exosmosis if the metal is in true solution and dialysis or ultrafiltration if the metal is in colloidal form. It is argued from the work of Freundlich and others that there is in fact a difference only in degree and not in kind between these phenomena.The physical chemistry of the process is first dealt with, after which examples of impounding structures in the field and in the literature are described, commencing with the present author9s original paper on impounding some years ago. Finally the possible applicability of the theory to regional replacement is discussed.