302 Relations of Trap-Bocks with Ores of Copper. 



part, separate the green and red gabbro from the serpentine 

 masses, which at times pervades these gabbros parallel to 

 the curves of contact, must be, it appears to us, the ema- 

 nations which have immediately followed the serpentine 

 eruptions. The cupriferous and plumbiferous amphibo- 

 lites of Campiglia are the different results of analogous 

 actions, insulated from the serpentines, but which are co- 

 temporary with them. Among mines of iron, the cele- 

 brated repository of Rio, in the Island of Elba, has appear- 

 ed to us to be. one of contact placed between the gabbros 

 and the less altered rocks, but subordinate to the ser- 

 pentine masses of St Catherine ; while the eruptive reposi- 

 tory of la Calamita, with its yenites and amphibolites, was, 

 like those of Campiglia, a more direct produce of subterrane- 

 ous action. Finally, we have mentioned that we consider the 

 oligistic iron, which the gabbros and stratified formations 

 have so often imbibed towards the points of contact with the 

 serpentines, as resulting from the same metalliferous emana- 

 tions. 



Such are the facts which we have illustrated in detail in 

 the Etudes sur les Mines ; let us now endeavour to find ana- 

 logous facts. 



The cupriferous repositories of Santiago de Cuba are ac- 

 quiring remarkable importance. In 1846, there were de- 

 spatched from that port, for Wales, 40,000 tons of copper ore, 

 that is to say, upwards of 6000 tons of copper. This enor- 

 mous produce has completely eclipsed the exportations from 

 Chili and Bolivia, whose ores now appear at Swansea only 

 in secondary proportions. The repositories thus developed, 

 well deserve the attention of geologists, and we are indebt- 

 ed to M. Arrieta for interesting information on the principal 

 mines, and the rocks which contain them. It appears from 

 his communication, illustrated by numerous specimens, that 

 the repositories are irregular and subordinate to masses of 

 greenstone and serpentine. 



The principal works are situated at six leagues from San- 

 tiago de Cuba, around the small town of Cobre, built for the 

 use of the miners, and which already contains from five to 



