396 PROCEEDINGS OF THE CALIFORNIA 



ores — as well as the manner in which certain substances, as barytes, now found 

 as sulphate, and true porphyry, now found as kaoline or lithomarge, have found 

 their present situation in the belt in question — all these would possess both 

 interest and importance in a high degree, could they be more definitely known. 

 Such questions, however, cannot be answered with certainty, and their discus- 

 sion here would lead us too far into the doubtful realm of chemical geology. 



But whatever may have been the agencies at Work, it is evident that there is 

 nothing in all this to remind us of a true vein formation. It appears that the 

 zone in question is neither a vein, nor generally speaking a system of veins. 

 On the other hand, it possesses emphatically in general the characteristics of 

 what the Germans style an impregnation — an impregnation indeed which exhibits 

 a certain regularity as being mostly confined within a narrow zone, and stretch- 

 ing through a considerable extent of country, but which within these limits 

 shows the greatest irregularity of form, and much variety of character. Veins 

 of quartz occur here and there within the belt ; but they are not more frequent 

 here than elsewhere, and their occurrence has probably little or no direct con- 

 nection with the peculiar character of the belt itself. There is very little that 

 deserves the name of quartz at Quail Hill, though much of the surface rock is 

 pretty highly silicious in character. 



The impregnation of the rock with metallic sulphurets, particularly with 

 sulphurets containing copper, has in certain localities been sufficiently powerful 

 and concentrated to assume, in greater or less degree, the characteristics of 

 segregated veins of limited extent. This has been the case at the Napoleon 

 mine, and also at Quail Hill, where there is, or was, a band of oxidized ores of 

 copper traversing the decomposed rock in a direction parallel with the general 

 stratification. This band consisted chiefly of the green and blue carbonates of 

 copper, mingled with ferruginous and earthy matter, and accompanied by 

 barytes. The last named mineral, so common a veinstone in other parts of the 

 world, but hitherto so rare in California, occurs here in considerable quantity. 

 Its form is granular compact, sometimes quite pure, but usually contaminated 

 and intermingled with other matters. Crystallized specimens of it have not 

 been found here to my knowledge. It is hardly probable that the barytes itself 

 contains either gold or silver ; yet it certainly occurs here in the most intimate 

 contact with both, as I have seen respectable particles of gold in place upon 

 the immediate surface of compact specimens of barytes — and a sample of heavy 

 concentrated barytic sand from the tailings of the mill, of sufficient fineness to 

 pass through a sieve of one hundred holes to the linear inch, yielded to the 

 assay over eleven dollars per ton in gold and silver. 



The thickness of the copper band varied from one to three or four feet. Its 

 outlines were indefinite, and its original characteristics of form, etc., much 

 obscured by the complete decomposition both of itself and the surrounding 

 rock. It was without doubt originally a segregated mass of sulphurets ; and 

 though it seems now to have nearly or quite run out and disappeared, it may 

 be found to come in again as such, in depth, uualtered below the line of surface 

 decomposition. 



Other bands of similar character may perhaps exist in the yet undeveloped 



