OF SANTO DOMINGO. 



89 



the identification, so his prophecy has received a better fulfillment than it merited. In 

 saying this, however, I do not wish to be understood as having the least desire to 

 disjiarage the really valuable work done by that excellent student. 



Before leaving this formation there is another subject that merits at least a passing 

 notice. Almost everywhere the metamorphosed slates carry quartz veins, sometimes 

 barren, sometimes auriferous. These veins are usually small, rarely more than a foot 

 or two in Avidth, although one instance occurs on the Upper Jaina River, where a 

 width of over twenty feet is attained. In no case have I had reason to suppose these 

 masses filled fissures, in the ordinary sense of the term. In every instance where a 

 good outcrop occurs, so that its nature could be clearly made out, the quartz is found 

 inter-bedded or inter-stratified with the slate, following its contortions and intimately 

 united on the sides. In other words they are true veins of segregation. They are 

 most numerous in the vicinity of the injected masses of orystalline I'ock. They occur 

 also quite abundantly in the whitish talcose rock of the main ridge, as for instance, 

 on the Bonao road, and again in the neighborhood of Yamasa. But one strongly 

 marked feature has been observed to characterize all of the veins. Those nearest to 

 the intrusive rocks are always gold-bearing ; and those at a distance from them are 

 invariably barren. This has been abundantly proven by innumerable examinations. 

 No vein-mining for gold has ever been undertaken on the island, but I have caused 

 numerous analyses to be made of specimens from various localities, always with the 

 above results ; and further, as a natural influence, every stream running through the 

 metamorphic rocks in the immediate neighborhood of masses of syenite carries gold 

 in its sands, while all of those running exclusively in the syenites, or at a great dis- 

 tance from them, are without the precious metal. Thus the ]Srigua and Jaina Rivers 

 are barren at their heads, but immediately on entering the slates they and all of their 

 tributaries are gold-producing. The upper waters of the ]!^izao, Ocoa, and their 

 upper branches carry gold, while the Majoma, entirely in crystalline rocks, is barren. 

 JSTot to multiply examples, the same may be said of all the north face of the Cibao 

 range, west of Santiago, while east of Yega in the north, and east of the Jaina River 

 on the south, that is, east of the eruptive rocks, no gold has ever been reported. 



It is also in this formation that the little copper of the IsTigua and the fine iron 

 deposits of the Maimon occur. These will be described in detail in their proper 

 places in connection with the description of the local geology. 



A. V. S. — VOL, XV. w. 



