124 Geological Communicaiions. 
2. The Gold of Mexico in a rock, equivalent to that which contains 
the Gold of the Carolinas; by Prof. Amos Eaton. 
Ar page 50, Vol. XVIII, of this Journal, I related facts intended 
to demonstrate, that the gold of the Carolinas was embraced in tal- 
cose slate rock; 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, &c. 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. Iam 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, §c. 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. 
Pror. Sirtiman.—T ue 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, 20 
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. 
until 
* Jn a letter, dated Dec. 22d, 1830. 
