300 
The American Geologist. ^'ovember, i904. 
700 feet above Lake Superior, and the chute of the richer 
streaks in the deposit is northward, and we may imagine the 
waters working down in that direction to re-appear over in 
the Allouez gap or up some fissure which may possibly have 
determined the gap. We see, therefore, that the question as to 
whether the copper was deposited by waters circulating in 
one fashion or another has a practical interest in guiding the 
search for the richest parts of the lode. Moreover, VsLn Hise 
has suggested that the richer parts of the lode — called chutes — 
will be found beneath upward bends if the waters of deposi- 
tion are ascending, beneath downward bends if the waters of 
deposition are descending. If he is right, wdiich I doubt, in say- 
ing that the copper of the Michigan lodes are deposited by 
ascending waters, the southern end of the Ahmeek and the 
northern part of the Kearsarge properties should be extra pro- 
ductive according to Hubbard's map of the Allouez gap area 
(\'olume M., Part II., Plate VII.). but if the waters are de- 
scending, the same area should be lean. 
In the first place we may premise that it is a settled ques- 
tion that the copper was deposited by water. All kinds of 
authority agree in this, although at one time a few geologists 
thought of its being inserted in a molten state. But native 
copper and native silver occur together, as they could not if 
thev were melted. They would at once be alloyed. Jewelry is 
often made of sections of nuggets of copper and silver, popu- 
larly known as halfbreeds, where the sharp and irregular line 
between the copper, and silver is beautifully displaved. We also 
find copper grown upon minerals, like analcite and prehnite, 
which one can fuse in a candle flame. It is not very rare to 
find a sharp crystal of dog-tooth spar entirely plated over 
with copper, and then the growth taken up again.* Pumpelly 
has given in Volume I. of our reports a most thorough dis- 
cussion of the way in which the copper occurs. A very in- 
teresting specimen, owned by Dr. Hubbard, shows a crystal of 
quartz which has Ik^cu corroded and mainly by native cop- 
per. Moreover, in the deeper part of the Ouincey mines. Dr. 
Koenig has found a water which is now depositing copper and 
contains 9 grams to the metric ton of the same. 
* See Volume i, Part II, Chapter III; also Volume vi, Part II, pp. 163 to 
165 of our reports. 
