418 QUICKSILVER DEPOSITS OF THE PACIFIC SLOPE. 



in the lack of cinnabar, but in the mechanical disintegration of the country 

 effected by the Post-Neocomian upheaval. To this are due the great irreg- 

 ularity of the deposits, the dissemination of cinnabar in minute fissures, or 

 as "paints," in the language of miners, and the small average size of the 

 deep-seated veins. Deposits may somewhere be found in firmer or less fis- 

 sured rock, but there only can strong, simple fissure veins be expected to 

 prevail in depth. Such deposits are exceptional everywhere. In the Al- 

 maden district ore is known to occur at over seventy points, but at only one 

 of them was the accumulation great enough to supply the world with mer- 

 cury for thousands of years. The Santa Barbara, at Iluancavelica, too, was 

 one of over forty known deposits in the same district. Systematic and in- 

 telligent prospecting is even more needful in mines on the Coast Ranges 

 of California than elsewhere, and the special attention of superintendents 

 should be directed to a study of the fissure system. This will almost in- 

 variably be ver}- complex, and can be satisfactorily made out onl}' by daily 

 study as the work progresses. ^Yhen a large part of the mine is abandoned 

 and closed, it is often impossible to find the key to the true distribution of 

 the fissures and of the ore chambers which accompany them. Helpless 

 groping, discouragement, and often the abandonment of property which 

 probably contains treasures often follow. An increase of geological skill 

 in the management of quicksilver mines would do much to offset the unfor- 

 tunately capricious distribution of ore. Good civil and mechanical engi- 

 neering is necessary, but not sufficient, to make the best of a quicksilver 

 mine, nor can occasional assistance supply the place of enlightened daily 

 study of geological structure. There is nothing novel in this warning, nor is 

 there any probability that so trite a piece of common sense will be heeded. 



