406 QUICKSILVER DEPOSITS OF THE PACIEIC SLOPE. 



no deposits in any part of the world offer such opportunities for the study 

 of the real maimer of deposition as tliose discussed in this memoir. The}^ 

 therefore constitute au exceedingly important example, and the question 

 whether the (piicksllver deposits of the Pacific slope include true veins of 

 cinnabar is consequently one of great and general interest. 



That fissure systems nuist underlie hot springs such as those of Steam- 

 boat and Sulphur llauk is evident, since otherwise the waters could not 

 reach the surface. Some geologists, however, are of the opinion that hot 

 springs deposit the minerals which they carry in solution only at their 

 orifices, and not in the fissure systems which lead to the surface. So far as 

 quicksilver and the accompanying characteristic minerals are concerned, 

 deposition is not actually or substantially limited to the surtace, as is shown 

 conclusively by Sulphur Bank, where ore has deposited abundantly at con- 

 siderable depths from ascending currents of water which are still intensely 

 hot. This ore, too, as was pointed out above, is of precisely the same char- 

 acter as that met in other mines a thousand or more feet from the surface. 

 The deposit of the deep mine at Sulphur Bank, however, is not a vein, 

 though here and there stringers of ore were found whicli dift'ered in no re- 

 spect from small veins. Indeed, since, as was shown in the earlier portior 

 of this chapter, the cinnabar is deposited in pre-existing openings, the form 

 which the deposit takes is determined by that of the fissure system. Whether 

 in a particular case a deposit assumes the form of a vein, an irregular body 

 (stock), or a reticulated mass (stockwork) does not depend upon the direc- 

 tion or the temperature of the currents of the solution, but upon the char- 

 acter of the fissure system. This system, again, owes its character to the 

 physical properties of the rock and the dynamical influences to which it has 

 been subjected. 



While in nearly all the quicksilver mines of the Pacific slope the por- 

 tions of the deposits at short distances from the surface closely resembled 

 the lower part of that at Sidphur Bank, say from the first level downward, 

 several of the mines have exhibited a much more regular structure in the 

 deeper workings than has been detected at Sulphur Bank. I have endeav- 

 ored to discuss each of them without departing from recognized standards 

 of description, but I have pointed out the inadequacy of the fiimiliar ter- 



