258 QUICKSILVER DEPOSITS OF THE PACIFIC SLOPE. 



practiced observer that the deposition has taken phxce from solution, and 

 not from vapor. The occurrence also limits the possibilities as to the 

 origin of the ore. The formation of sulphur is still going on, and so also 

 must be the decomposition of the basalt and the deposition of pasty hy- 

 drous silica. Tlie association of cinnabar with the sulphur and its deposi- 

 tion along the concentric partings of the decomposed basalt blocks close to 

 the fresh nuclei show that cinnabar is either now being deposited or that 

 its deposition has ceased only very recently and must have gone on while 

 the conditions were almost precisely those now existing. 



The copiously flowing springs which existed here before mining opera- 

 tions began and the sulphur deposition show that the waters rising toward 

 the surftice come from a considerable depth. Tliis must have been the 

 case during the entire period of sulphur deposition. The ore cannot have 

 leached downward from the basalt into the underlying rocks, nor can a 

 trace of quicksilver be detected in the undecomposed basalt. Neitlier can 

 the quicksilver have been derived from the layer of recent lake deposits un- 

 derlying the basalt. This layer is thin, at least in places, and lies hundreds 

 of feet above some occurrences of the ore. The original source of the quick- 

 silver must then have been either in the Knoxville beds, chiefly sandstone, 

 or below them. This sandstone is proved by microscopic examination to 

 be arcose, or granitic detritus, and abundant evidence has been given in 

 preceding chapters to show that granite underlies the Coast Ranges. The 

 source of the quicksilver is consequently either granitic detritus or granite 

 or it lies below the granite. Further than this the facts at this one locality 

 do not justify conclusions as to the origin of the ore. 



soifataric springs. — A vcry remarkable feature of this mine is the abundance 

 of hot springs, frequently carrying gases. These gases are often ammoni- 

 acal and many of them carry sulphureted hydrogen. Others again have 

 a nauseous smell which plainly indicates an organic origin. An analysis of 

 gas from the Hermann shaft gave — 



Carbon dioxide, CO- 89.34 



Hydrogen sulphide, H-S 0.23 



Marsh gas, CH< ".94 



NItrogeD, N 2.49 



Tot.al 100.00 



