402 QUICKSILVER DEPOSITS OF THE PACIFIC SLOPE. 



Sulphur Bank have been produced. Both of these locahties present at the 

 surface ver}- marked pecuUarities, wliich miglit be thought to divide tlieni 

 sharply from the deep mines, such as New Almaden, and to permit of no 

 inference from one to the other as to the genesis of ore, though, excepting 

 for the occurrence of native sulphur at the active springs, the difference 

 is physical rather than mineralogical. At Steamboat no considerable effort 

 has been made to follow the deposit, none of the excavations, so fiir as 

 I could learn, being over fifty feet deep. At Sulphur Bank, which is so 

 closely similar to Steamboat Springs, one chimne}' of ore has been followed 

 down for several hundred feet, and the ore found in the lower workings is 

 entire]}^ indistinguishable in any way from that in the cold, deep mines to 

 the soutli. It is the same association of cinnaljar, quartz, iron sulphides, 

 and carbonates. It contains no free sul[)hur ; it permeates very porous 

 sandstone, but only fills the crevices of dense sandstones and shales, just as 

 is the case at New Idria. 



The Manzaiiita mine, in Colusa County, carries gold as well as cinna- 

 bar. The ores of Sulphur Bank and of Steamboat, as well as those of the 

 Baker and Redington mines, are also auriferous. The Manzanita, further, 

 contains a little stibuite (as did the Lake mine at Knoxville), pyrite, quartz, 

 calcite, and considerable quantities of bitumen. The ore is irregularly de- 

 posited in the crevices of the rock. Close by issue strong, hot sulphur springs, 

 and the surrounding country shows that similar waters have not long since 

 issued from many other points now dry. Tliough this deposit has been some- 

 what eroded, large quantities of free sulj)liur still remain in portions of it. It 

 thus exhibits the closest analogy to Sulphur Bank, though active springs 

 no longer issue from it. It differs from Sulphur Bank, however, in the fact 

 that no eruptive rock exists in the iuniiediate neighborhood, nor, so far as is 

 known, for a distance of several miles. This is an important peculiarity. 

 Other small quicksilver mines occur within short distances of the Man- 

 zanita. 



The neighborhood of ^tna Springs, in Napa County, is very instruct- 

 ive. Here within a circle of three miles in diameter lie numerous deposits 

 belonging to the Napa Consolidated and the vEtna Companies. From one 

 of these, the Valley mine, now abandoned, flow the hot siilphur springs 



