MINING GEOLOGY 
347 
Samples of the Cranberry low-grade ores were treated at the 
Bureau of Mines Experiment Station, at Minneapolis, where 
special tests were made on the possibilities of concentrating these 
ores. These results seem to indicate that a satisfactory method 
of concentration may be readily devised. By dry method a good 
smelting product, assaying better than 56 per cent iron and only 
1 per cent phosphorus may be obtained through concentrating 
two and one-half tons of ore into one. 
A vast new tonnage of iron ore is made available. 
Pratt. 
Circulatory Cycles of Ore-hearing Waters. Movement of ore- 
bearing groundwaters is not a simple sinking of meteoric waters 
into the earth’s crust, but a complex and composite mingling of 
currents from many sources. On the theory of the meteoric ag¬ 
glomeration theory of the origin of the earth, the original and 
often the immediate source of ore-materials can hardly be in na¬ 
ture so largely magmatic as it is vadose. Qualified in some ways 
and strengthened in others, the general arguments of Forchham- 
mer, Sandberger, Winslow, Van Hise and Bain assume a new 
interest and an added value. The main shortcoming, if such it 
really be, is merely in ascribing a sole, or principal, origin of the 
ore-materials to rock-weathering, when a somewhat broader in¬ 
terpretation of the facts seems necessary. 
Ore deposits in the main are precipitated from aqueous solu¬ 
tions. Solution, transportation and deposition of ore-metals are 
distinctly processes operating through the medium of subterranean 
waters. The sources of the ore-minerals, the courses which they 
follow through the geologic formations, and the immediate causes 
of their localization, are factors of prime importance in the con¬ 
sideration of ore-genesis. Obscure as are the migration and changes 
of ore-materials it is possible, as will be seen presently, to repre¬ 
sent graphically their general courses through the earth. 
The various phases of primary ore-genesis may all be reduced 
to four principal groups: (1) extraction from sea-water; (2) 
inclusion of metallic minerals as accessories in the igneous rocks 
themselves and the subsequent liberation and segregation of the 
ore-materials through weathering-processes; (3) production of 
metalliferous bodies in connection with rock-masses in a molten 
