78 Feather stonhaugh's Geological Report. 



in Russia, that the sands of some of the platinum mines re- 

 sembled those Brazilian sands in which diamonds were found. 

 Humboldt subsequently perceived the same resemblance ; and 

 in consequence of his suggestions, a search was made, and 

 very fine diamonds|discovered : so that the Ural mountains, 

 which bear a strong resemblance to portions of the gold region 

 of the United States, produce gold, silver, platinum, and dia- 

 monds.* 



The carboniferous limestones are the next metallic deposi- 

 tories, both in Europe and the United States, of which some 

 account was given in my report of last year ; and as it will 

 occur to me in another part of this report to speak of the coal 

 measures of the United States, with their associates, salt and 

 iron, I shall pass on to a brief review of the organic remains 

 found in the beds which have been enumerated a subject of 



* A late paper by Sir David Brewster, in the Transactions of the Geological So- 

 ciety of London, vol. 3. part 3, on "the structure and origin of the diamond," 

 brought to my recollection a note which Professor Del Rio sent me some years 

 ago, of which the following is a translation : 



" I was shown, towards the end of 1822, two small diamonds, which were stated 

 to be brought from the environs of Sultepeque; that is not exactly their locality, 

 but it is upon that route. In truth, D. Vincente Guerrero found in the Sierra 

 Madre, in the south of Mexico, upon a height of land distant a day and a half 

 from Tdtela del Rio, in descending by Coronilla, some geodes, with amethyst and 

 rock crystal in their interior. These geodes were smallest towards the surface, 

 and only became larger in digging deeper down. On breaking these geodes, true 

 octohedral and dodecahedral diamonds were found in some of them, resembling 

 those of India and Brazil. I am not too credulous, but I have been assured of the 

 fact by persons who deserve to be confided in. This unexpected manner of find- 

 ing diamonds becomes the more remarkable, because the geodes are not found dis- 

 seminated in the loose soil, but are imbedded in a hard and stony mass, rendering 

 it necessary to get them out with pickaxes and crowbars." 



Mr. Del Rio subsequently informed me that General Guerrero had personally 

 confirmed this account to him, adding, that the geodes containing the precious 

 stones rattled when shook ; but he had never been able to ascertain, from any 

 quarter, the geological character of the bed containing the geodes. The late Dr. _. 

 Voysey states the matrix of the diamonds in southern India to be a sandstone 

 breccia, of the clay-slate formation, which may be the case with this Mexican lo- 

 cality; I have frequently written to Mexico without obtaining any satisfaction on 

 this subject. 



