124 Geological Communications. 



2. The Gold of Mexico in a rock, equivalent to that which contains 



the Gold of the CaroUnas; by Prof. Amos Eaton. 



At page 50, Vol. XVIIJ, of this Journal, I related facts intended 

 to demonstrate, that the gold of the Carolinas was embraced in tal- 

 cose slate rock 5 and that its gangue is quartz, of an intermediate 

 character between the milky variety contained in argillite and the 

 translucent variety of the granite. I have now before me more than 

 one hundred specimens of the gold ore of Mexico, with its gangue 

 and rock walls ; both of which precisely resemble those of the Caro- 

 linas. These specimens, as well as numerous others of the silver, 

 quicksilver, copper and zinc, of that country, were collected by 

 George Robinson, Esq. of Curracoa, W. I. (whose son is a member 

 of this school,) who has been engaged for twenty years in exchang- 

 ing European goods for bars of Mexican gold, he. In this collec- 

 tion are specimens from all the most important gold mines, extending 

 north and south through a district of country of more than a thousand 

 miles. I am authorized to say, that all these mines are contained, 

 chiefly, in the talcose slate ; and wholly so as a central range. By 

 this expression I wish to be understood, that the mines sometimes 

 extend laterally into the adjoining rocks, as the hornblende rock, 

 mica slate, &fc. but that the main body of every mine is in the talcose 

 slate rock. 



Rensselaer School, Troy, March 3, 1831. 



3. Scratches on elevated strata of horizontal graywacke in the Al- 

 leghany range ; probably deluvial. Communicated to Prof. Ea- 

 ton, by Judge William A. Thompson,* of Sullivan county, N. Y. 



Prof. Silliman. — The unpretending character of Judge Thomp- 

 son, deprives the republic of science of much valuable information. 

 He is the proprietor of Thompson town, is perfectly at leisure, and 

 a nice observer. His estate lying in the most interesting part of the 

 Alleghany range, gives him peculiar advantages. 1 have drawn from 

 him the result of some of his geological observations. 



Yours respectfully, Amos Eaton. 



* la a letter, dated Dec. 22d, 1830. 



