156 ANNUAL EEPOET SMITHSONIAN INSTITUTION, 1917. 



named. Even now 100 ounces or so are washed annually from the 

 rivers of Porto Rico and perhaps the same amount from those of 

 Haiti. The gold seems to be derived from the vicinity of intrusives 

 such as diorite and serpentine, in part, if not altogether, of post- 

 Cretaceous age. The gold placers of Cuba were situated in the mid- 

 dle part of the island, in the Santa Clara and Puerto Principe Prov- 

 inces. Those of Haiti are said to have been highly productive in 

 the early days of the Spanish regime. 



CENTRAL AMERICA. 



The Cordillera does not continue as an unbroken chain from Mex- 

 ico into Colombia. The structure of Central America is complex, 

 with short easterly trending ranges of older rocks in Guatemala and 

 Honduras. Farther south these older rocks are submerged beneath 

 Tertiary and Recent lavas, in part andesitic. The Isthmus connect- 

 ing the two Americas is in fact marked by a chain of volcanic cones, 

 many of which are active. 



Though some mineralization is found in the older rocks of pre- 

 Tertiary age, the valuable deposits are mainly in andesitic or rhyo- 

 litic rocks, and belong clearly to the class of veins which were formed 

 near the surface. Some of these yield mainly gold, but in many cases 

 they are of the well-known type in which gold and silver occur to- 

 gether without notable amounts of the baser metals. The annual 

 production of Central America ranges from $1,500,000 to $1,500,000 

 in gold and from 50,000 to 75,000 kilograms of silver. 



Guatemala contributes but little, .though there are many prospects 

 and placers on Motagua River on the Atlantic side. 



Honduras has the reputation of great richness. Its placers of 

 Olancho and Choluteca w^ere worked by the early conquerors. At 

 present the greatest part of its production comes from the gold- 

 silver mine of Rosario near Tegucigalpa. The Republic is the largest 

 silver producer in Central America. Gold to the value of about 

 $600,000 is produced annually in each of the three States, San Sal- 

 vador, Nicaragua, and Costa Rica. In Nicaragua rich placers have 

 been worked in the Prinzapolca and other Caribbean rivers, and the 

 gold mining district of Pis-pis in the northeastern part of the Re- 

 jDublic has lately attracted much attention. Costa Rica has had a 

 considerable production from the placers of Monte Aguacate. The 

 Abengarez and Montezuma lode mines, on the Pacific side, are now 

 the chief producers. In San Salvador the production comes largely 

 from the Butters mines. All of these veins appear to be contained 

 in andesite or rhyolite. 



We find the same condition in Panama, though at present there is 

 little production from this State. The Espiritu Santo mine at Cana 



