31 



Feet. 



West Adit 100 



East " 535 



Tr ain Track. . . 430 



Total length of Adit Tracks 1,065 



Power of Lode, 12 feet; dip of Lode, 70 east. Strike, north and south. 

 Aggregate amount of ore reduced, 1855, 1,692 tons. Average value, $20. 



KEYSTONE MINE, AMADOR, AMADOR COUNTY. 



This mine, like that of the Eureka, was one of the pioneer operations of the 

 State. The mine and reduction works are situated but a short distance west of 

 the town of Amador, on a small tributary of Amador Creek. 



The first permanent workings of this mine were commenced in the early part 

 of 1853, and though superficial in their character, were prosecuted with vigor for 

 a considerable part of that year. At the close of 1853, and in the early part of 

 the following year, the old workings were abandoned, from the insecurity of the 

 artificial supports used during the preceding period. 



It was at this time that the necessity of more permanent supports for the exca 

 vations became apparent to the conductors of the mine, and during that year 

 they commenced their permanent structures in the underground operations, their 

 first movement being the cutting of a main shaft of sufficient capacity to afford 

 easy ingress and egress from the main adit to the lode below its level. During 

 1854 this shaft was driven to the depth of eight fathoms on the vein, and con 

 forming to its dip, and from the top to the bottom was timbered heavily with oak, 

 and the angles snugly tenoned and jointed, the ceiling being put in with heavy 

 planking, and closely squared. By this tedious and expensive process the mine 

 was safely secured from falling in, the 'upper part of it at least, a result which 

 must have ensued had the old system of working been persisted in. The old 

 works above the main adit were still in a weak condition, and began to present 

 many features of falling in, and which would have produced serious inconvenience 

 had they neglected to secure it in a proper manner. 



An inclined shaft was accordingly commenced that would connect that sunk 

 from the end of the adit with the surface, in a direct line of inclination. This 

 was done during 1855, and the depth of that portion of the shaft above the adit 

 was seven fathoms. 



This whim-shaft was cased with solid timber from top to bottom, and put in 

 with close joints, as it became necessary to use this heavy material in place of 

 planking, from the loose character of the surrounding ground. The ores are 

 now raised by a horse whim, through the line of shafting as described, and landed 

 at the* end of the main adit, from whence they are conveyed on train-ways to the 

 reduction works, about four hundred feet north of the entrance to the mine. 



During 1855 the sinking on the lode in a line with the whim-shaft, has been 

 five fathoms, and from this depth the lower level has been driven one hundred 

 feet north, and south about twenty feet. The upper gallery has been driven each 

 way but twenty -five feet. 



The lode at the depth of twenty-one fathoms, has a power of nine feet for one 

 hundred feet in length. The ores of this mine are highly pyritous, and strongly 

 impregnated with graphite, the latter mineral imparting at times a black, mottled 

 appearance to the ores, and at others a ribbond-like form, giving the idea of true 

 lumination. 



