240 GEOLOGICAL RECONNAISSANCE OF THE DOMINICAN REPUBLIC. 



whether any large, persistent vein exists in so shattered a volcanic rock. 

 Although a considerable amount of copper ore occurs here and although 

 some of it may be of high grade, the existence of enough ore to be profitably 

 worked is doubtful. 



ORE DEPOSITS ON SAN FRANCISCO HILL. 



The general geology and the character of the mineralization on San 

 Francisco Hill are very similar to that on Bucaro Hill. The accessible 

 openings and outcrops, however, show ore as much as a meter wide along 

 a few of the numerous slips. Sample No. 88 is a channel sample of a meter 

 vein running N. 45° E., and dipping 40° S., and the result of its assay is 

 given in the table on page 241. It is possible that ore running 10 per cent 

 or more can be readily picked from some of these veins, as is reported to 

 have been done. Probably much richer ore than this can be found occa- 

 sionally in small quantities. Garrison 1 states that on the crest of this 

 hill is the beginning of a mineralized shear zone that extends north-north- 

 east for several miles. According to Garrison the zone is more or less 

 regular, but the mineralization along it is uncertain and discontinuous. 

 During the present investigation, no time was available to trace this zone 

 through the dense vegetation of the hill. 



Some of the veins on San Francisco Hill may be large enough and rich 

 enough to be worked profitably on a small scale under favorable conditions, 

 but it is virtually certain that the ore bodies are discontinuous and 

 irregular. 



LA RAMA PROSPECT. 



The new prospect of Doctor Harootian in the Platanito district differs 

 somewhat from those described above. The most important difference is 

 that the ore contains more gold. Galena occurs in one of the openings 

 here but is not found elsewhere in the district. The specular hema- 

 tite found at the Bucaro and San Francisco workings was not seen here. 

 The quartz contains a little gold in blebs visible to the eye and some chal- 

 copyrite, pyrite, and galena. Doctor Harootian states that his assays 

 made at Naranja Dulce indicate a value of more than 5 ounces per ton in 

 gold and negligible amounts of silver. Assays, made by Ledoux & Co. (see 

 table on p. 241), of samples collected during this investigation indicate a 

 lower content of gold. As the gold occurs in part in large blebs that are 

 easily visible to the eye, no two small grab samples are likely to agree 

 closely on assay. The gold in the three samples from the principal opening 

 at La Rama varies directly with the copper. On the other hand, sample 

 No. 85, from the dump of one of the other openings at La Rama, is very 

 high in copper and low in gold. The sample carrying lead carries more 

 silver than any of the others. 



1 Garrison, F. L., op. cit., p. 308. 



