458 KANSAS CITY REVIEW OF SCIENCE. 
solutions, known also as copper pyrites, the ore being a mechanical combination- 
of copper, sulphur, and iron. These pyritous ores are known to occur in very 
large quantities, sometimes is well defined veins, also as deposits, being worked 
not only for the copper values, but also for the gold and silver occurring with 
them ; this is the case with the Colorado copper ores. They are also extensively 
worked in Canada, Spain, and other parts of Europe, and I am quite certain also' 
in the Southern States of this country, for sulphuric acid as well as the copper 
product. Where utilized for the acid, the ores are found to exist in very large 
(so-called) deposits con bined with a silica gangue; and surprising as it may seem, 
even where such ores have been worked for centuries in Europe, I know of no 
record which states that they have ever been worked out. 
Having got our copper into this condition, and exposed to atmospheric 
agencies, the next step in nature is, apparently to undo what she has so labor- 
iously built up. Without taking tim.e into consideration at all, comparatively 
speaking, copper pyrites are very readily acted upon by meteoric agencies, that 
is, rains, frosts, and snow waters help the ores to oxidize, the sulphur is set free,, 
washed out, and the residue is oxides of copper and iron ; notably the green and 
blue carbonates of copper. 
Now the salts of copper in this condition are much more soluble than the 
iron oxide, which results in a continual leaching process gradually carried on for 
ages upon ages, until all of the copper is leached out from amongst the iron, and 
accumulates further down amongst the vein matter, quartz ; this concentrated 
oxide is generally cuprite, or red oxide of copper, very rich, and giving over 
fifty per cent metallic copper. With no geological disturbances in the immediate 
locality this gradual change would keep on until all of our first formed pyritous 
ores would be changed to concentrated copper oxides ; concentrated at times to 
such a degree as to actually show spots, crystals and other small particles of 
really metallic copper, as a natural occurrence. 
Let some shght geological change now occur, by which the iron ore of the 
surface is eroded away, exposing the large mass of accumulated copper oxides. 
We have the illustration of this method of occurrence in New Mexico and 
Arizona ; where the most easily reduced of all copper ores are found in the form 
of almost mountains, or vast deposits of copper oxides, and the product from 
these is, to-day, successfully competing with the Lake Superior product. 
The metallic copper from the Lake Superior mines is the purest form of 
native copper now known, and the duplicate of this region has been widely 
sought for on the American continent for many years, but so far unsuccessfully; 
or at least if found, there has not been any attention attracted to it, as would 
naturally be the case if found in fact; but this is digressing somewhat. 
Having shown the first two steps of copper occurrence as known, it remains 
to reason out the Lake Superior copper region from the last explained. 
We can rightfully assume, for illustrative purposes, that we have a very large 
formation of quartz, mineral bearing, originally containing copper pyrites, which 
through ages of time, under the conditions described, have changed to the con- 
