CHEYSOLITE MINE. 459 



ally supposed to come. Mining was, therefore, conducted without any defi- 

 nite system. Drifts were run here and there, up and down, wherever ore 

 could be found, so that it was extremely difficult in traversing them to form 

 a clear idea of the actual extent and form of the ore bodies or to know 

 whether or not important ground still remained unprospected. When Mr. 

 W. S. Keyes took charge of the mine a new and more rational system of 

 development was adopted. A large three-compartment shaft, the Roberts 

 shaft, was sunk in what it was supposed was the deepest part of the ore 

 horizon, and from this shaft a system of horizontal drifts was run off at two 

 or three different levels, with a regular system of rectangular cross-cuts at 

 given distances. In this way it was possible to map out the shape of the 

 ore bodies, and it soon became evident that the vein material occurred as an 

 interstratified mass between two sheets of porphyry, somewhat irregular 

 and corrugated, but basining up to the surface on the southwest and north- 

 west. With the increased facilities for handling ore given by a large shaft 

 and by level tramways leading from every part of the mine to it, the work 

 of exploration could be pushed much more rapidly and the extraction ot 

 ore proportionately increased. The old workings of ihe mine were further 

 explored and considerable ore was discovered where the bonanzas had been 

 supposed to be exhausted. Entirely new bodies of ore were also found to 

 the west and northwest of the shaft, continuing irregularly up to the out- 

 crop as shown on Sections A, K, and L. None of these bodies was of so 

 great continuous extent or so rich in silver as the main ore body extending 

 eastward from Vulture No. 1. The most extensive and the richest was that 

 developed near Chrysolite No. 4. 



In the drifts running southward from the Roberts shaft to con- 

 nect with the Chrysolite No. 1 workings a body of Gray Porphyry 

 thirty to forty feet in thickness was cut, which has since been traced 

 eastward as far as the Robert E. Lee mine. In the Chrysolite ground 

 this body of porphyry has a dip of 45 to the northeast, but farther north 

 it stands apparently nearly vertical, and is, therefore, assumed to be an 

 interrupted dike. It extends much farther east and west than is shown on 

 the map, being exposed by drifts from the lower levels where it is wanting 

 in these directly above them, showing that it tapers upwards. In the north- 



