Featherstonkaugh^s Geological Repori. 77 



of extended lines of white quartz running on the surface in a 

 direction from N. N. E. to S. S. W., and frequently with an 

 almost vertical inclination. In the great geographical extent 

 of that region here, many portions of which are yet unexplored, 

 there may be rich deposites contained in mineral masses of a 

 different character, as is the case in Brazil, upon the Gongo 

 Soco estate, of which a brief description may be useful. 



The gold in this locality has been occasionally so abundant, 

 that 140 pounds have been extracted in one day. The bed 

 in which the gold is found is called jacotinga in the country, 

 and rests upon a ferruginous talcose state, resembling that of 

 various localities in Virginia. The jacotinga itself consists 

 of quartz and micaceous iron, and the whole mass is in a some- 

 what soft state of decomposition. It has a direction from east 

 to west, and is of a variable thickness, with a limited extent. 

 Towards the centre of this bed, a subordinate bed or vein is 

 found, of a brownish-black color, of a softer quality than the 

 general bed, and more or less distinct from it. It is from three 

 to six feet in thickness, and consists of layers of manganese 

 from thin lines to two or three inches in thickness, with talc 

 and iron glance in irregular strings and nests. It is in these 

 dark-colored layers of manganese that the rich strings and 

 bunches of native gold are found, which is also invisibly dis- 

 seminated among the layers. 



When the auriferous region of this country shall have been 

 more generally examined, other associate metals may possibly 

 be discovered. In the Ural, platinum has been abundantly 

 found, but more generally on the western or European side ; 

 the gold washings on the Asiatic side giving comparatively a 

 small quantity of platinum. Baron Humboldt also states that 

 the Call chain of the Cordilleras, in South America, separates 

 the gold-bearing sands of the eastern declivity of Popayan 

 from the sands of the isthmus of the Raspadura of Choco, 

 which are rich in platinum as well as gold. These analogies 

 are interesting to this country. Engelhaidt remarked, when 



