446 QUICKSILVER DEPOSITS OF THE PACIFIC SLOPE. 



being soluble in ii very limited class of solvents, and it is difficult to imag- 

 ine a solution of cinnabar rising through several miles of rock at constantly 

 diminishing temperatures and pressures without losing a large part of its 

 contents. If high pressures and temperature have in this case anything 

 like the effect which the theory of solutions and experiments on the solu- 

 bilit}' of substances at high pressures lead one to suppose, solutions which 

 below the granite would be only partially saturated would become super- 

 saturated long before they reached the surface, and ciiniabar deposits thus 

 formed, if they cropped out at all, would extend down into the granite, 

 probably growing stronger with increasing depth for long distances. This 

 is emphatically not the case with the deposits of the Pacific Slope. 



Hypothesis of derivation from granite. If, OU tlie Otlier liaild, OUC SUppOSeS that 



the granite is the original habitat of tlie quicksilver, the observed relations 

 become simple and natural. The solutions of sodium sulphide accompanied 

 by carbonates, chlorides, etc., which followed the actual course "of lava cur- 

 rents, would then have no opportunity to take up quicksilver ; while simi- 

 lar solutions which diverged from the course of the lava into the surround- 

 ing country rock would decompose the metalliferous components of the 

 granite, forming and dissolving mercuric and ferric sulphides and bringing 

 them to the surface in greater or smaller quantities, according to the course 

 of the currents and the composition of the granite. Deposits would then 

 form, not in volcanic vents proper, but at the points where thermal springs 

 due to volcanic action issue from the country rock. Such deposits would 

 be of very variable size. Where the channels leading up to the springs 

 were simple and of small extent, mere traces of ore would reach the sur- 

 face ; while, when a limited system of openings at the surface gave exit to 

 waters which had flowed through extensive masses of shattered metallifer- 

 ous granite, larger deposits would be produced. Now, in fact, tlie localities 

 in which ciiuu)l)ar is found on the Coast Ranges are numberless ; they are 

 characteristically associated with hot springs ; they do not occur in volcanic 

 vents, ))ut are usually at no great distance from such vents. Of all the 

 more important niines New Idria alone is not in the innnediate neighbor- 

 hood of lavas, the nearest mass of basalt known being some ten miles dis- 

 tant. 1)111 hilt, alkaline springs, similar to tliosc^ immediately associated 



