114 
ECONOMIC 1 GEOLOGY OF SILVERTON QUADRANGLE, [bull .m. 
the water gave a strongly acid reaction, and a deposit of ferric 
hydroxide or basic ferric sulphate, together with some silica, had set- 
tled in the bottom of the bottle. The total contents of sample were 
subjected to partial qualitative tests by Dr. Hillebrand, with the fol- 
lowing results: 
Partial analysis of water from spring above the Guston mine. 
Constituent. 
Remarks. 
Constituent. 
Remarks. 
S0 3 
Very much. 
Very little. 
Much, about 214 parts per 
million. 
Much. 
Do. 
Not tested for. 
Do. 
About 75-80 parts per mil- 
lion. 
Zn 
A little. 
CI 
Mil 
Alo0 3 
Ni 
>Not tested for. 
Co 
Fe. 
Cu 
0.65 parts per million. 
Ca 
Pb 
Na -.. 
Mo 
As 
j 
K 
> Absent. 
SiO.. 
Ag 
P.,0 5 .. 
) 
It appeared from these preliminary tests that the water of this spring 
carried no appreciable amounts of the important ore-forming metals, 
and it was not considered advisable to devote time and labor to further 
chemical work upon it. It was at first hoped that its analysis might 
throw some light upon the nature of the solutions which originally 
deposited the Red Mountain ores. But the preliminary tests indicate 
no characters that might not be expected in ordinary meteoric waters 
after passing for some distance through the mineralized and altered 
rocks of the immediate vicinity. There is, so far as known, no defi- 
nite evidence connecting the ferruginous springs of this region directly 
with the original processes of ore deposition, nor is it necessary to 
assume that the waters issuing from them have come from deep-seated 
sources. The mine waters of the Yankee Girl and Guston are said to 
have carried much copper in acid solution. This is to be expected 
wherever surface waters carrying oxygen pass downward for any dis- 
tance through pyrite and chalcopyrite. The presence of considerable 
alumina has an important bearing on the question of the metasomatic 
alteration of the country rock, as will be later shown. 
METAMORPHISM OF THE COUNTRY ROCK IN CONNECTION WITH 
ORE DEPOSITION. 
The metamorphism or change which has been effected through the 
agency of the mineral -bearing solutions (hydrothermal metamor- 
phism) in the rocks adjacent to the ore bodies differs very markedly 
in degree, and to a less extent in character, in different portions of 
the quadrangle. 
The mode of alteration is in general by metasomatism (literally 
change of body), by which is meant the process by which a mineral, 
