858 



ancient granites are also the least destitute of 

 metals; and several auriferous rivers and tor- 

 rents in the Andes, in the Salzbourg, Fichtel- 

 gebirge, and the tableland of the two Castiles, 

 lead us to believe, that these granites sometimes 

 contain native gold, and portions of auriferous 

 pyrites and galena disseminated throughout the 

 whole rock, as is the case with tin, and magnetic 

 and micaceous iron. The group of the moun- 

 tains of Parima, several summits of which attain 

 the height of one thousand three hundred toises*, 

 was almost entirely unknown before our visit to 

 the Oroonoko. This group however is a hun- 

 dred leagues long, and eighty broad ; and though 

 wherever Mr. Bonpland and I traversed this vast 

 group of mountains, it's structure seemed to us 

 extremely uniform, it would be wrong to affirm, 

 that it may not contain very metalliferous tran- 

 sition rocks and micaslates superimposed on the 

 granite. 



I have already observed, that the silvery lus- 

 tre and frequency of mica have contributed to 

 give Guyana great celebrity for metallic wealth. 

 The peak of Calitamini, glowing every evening 



* The loftiest mountains, which have hitherto been mea- 

 sured in Brazil, are only nine hundred toises high j such are, 

 Itacolumi, in the Capitania of Minas-Geraes (near Villa- 

 rica), the Serra d'Xtambe, the Serra de Caras, &c. See the 

 excellent memoirs of M. d'Eschwege. (Journ, von Brasilien, 

 1818, Vol.i, p. 213). 



