ECONOMIC GEOLOGY. 



Assays of samples from the San Francisco concession. 



241 



The recent heavy rains had caused slides that made it impossible to see 

 very much in any of the four small openings, which penetrated the hill 

 6 meters. There is a shear zone over a meter wide near the bottom of the 

 opening and wider near the top, where it is cut off by a slip. In the shear 

 zone there is shattered chloritized volcanic rock full of quartz stringers, 

 with some sulphides and a few rusty streaks. The ore deposit is reported 

 to have been about 40 centimeters wide where it was first struck and to 

 have widened steadily as it was followed. The strike varies from about 

 N. 30° E. at the entrance of the opening to a few degrees north of west 

 at the face. The dip was steep to the southwest at the entrance; at the 

 face it is nearly vertical on the hanging wall and 25° N. E. on the foot wall. 



The low assay results of the samples taken at the prospect are disappoint- 

 ing but are not conclusive. In a deposit of this type considerable varia- 

 tion in tenor is to be expected. Not enough prospecting has yet been done 

 to enable any one to form definite opinion as to the quantity of ore likely 

 to be found, but the showing so far made warrants further development. 

 The country rock is the same shattered volcanic rock that is found at 

 the Biicaro and San Francisco workings. The vein or shear zone may 

 be discontinuous, but the small opening made shows a more definite and 

 promising zone than any seen in the accessible workings at the other 

 localities. 



CONCLUSIONS. 



Copper ore, some of it of excellent grade, occurs at numerous places in 

 the San Francisco Concession. Many of the tunnels are now caved, so 

 that it was impossible to determine the quantity of ore developed, but it 

 is evidently small. In the tunnels now accessible no ore is blocked out, 

 and there are only scanty indications of ore. The property has practically 

 no present value as a copper mine. 



The gold prospect called La Rama, in the Platanito district, has not yet 

 reached the stage at which definite conclusions can be reached as to its 



