ANALYSIS OF THE CONCENTRATION PROCESSES 6 



and physical conditions which prevailed during former stages in the 

 earth's history; and in the same manner, also, that fossils enable one 

 to trace the evolution of species, genera, etcetera, of animals and plants 

 or to follow the migrations of floras and faunas during former geological 

 periods, so a knowledge of present processes of concentration shed light 

 on many pages of geological history which otherwise would remain in 

 shadow. Not only do the principles governing the concentration of 

 mineral matter furnish a tool for use in general geological investigations, 

 but one which is of practical utility to the economic geologist and mining 

 engineer. For example, it is only when the processes of concentration 

 which have led to the formation of a bed of coal or that filled a fissure 

 with ore are understood that predictions worthy the name can be made 

 as to the extent of such deposits or reliable advice given in reference 

 to the localities and associations most suggestive of their presence. 



In a preceding paragraph examples of what is meant by the term 

 concentration were cited. One of the processes, namely, the separation 

 of gold, platinum, etcetera, from associated debris is obviously controlled 

 by physical conditions; another, the precipitation of calcium carbonate 

 and silica from the waters of springs, is dependent in part at least on 

 chemical conditions; and still another, the secretion of carbon in the 

 tissues of plants, necessitates the action of vital functions. These illus- 

 trations suggest a method for classifying the various processes by which 

 mineral matter is concentrated, thus rendering it practicable to give 

 concrete shape to the tool we wish to fashion. The suggestion is that 

 the many and varied processes by which concentration is brought about 

 may be arranged in orderly sequence with reference to the nature of the 

 chief or controlling force by which the selection, transportation, and 

 deposition of the material segregated is rendered possible. 



Analysis op the Processes of Geological Concentration 



The activities which lead to the separation of one kind or of a definite 

 combination of matter from other kinds or combinations of matter, the 

 transfer of the selected material to a new locality, or more or less com- 

 plete isolation of a residue, precipitate, etcetera, are : ( 1 ) physical force, 



(3) chemical force, (3) the intimate and interdependent combination 

 of molecular and atomic activities termed physical-chemical force, and 



(4) the property inherent in living organisms which is designated as 

 vital force. Under the influence of one or another of these four divisions 

 of energy as a dominant factor, it seems practicable to arrange all the 

 processes of concentration now in operation or which can be shown to 



