576 Analysis of Nellore Copper ores. [Oct. 



in this rock, and it is generally known to contain various metallic veins, as gold, 

 silver, and copper. 



" Subordinate to the former is green-stone slate, in mighty layers, often as to 

 appearance constituting the principal rock of a district for many miles. This is 

 the case about Guramanypenta and the other mining places. The layers or 

 stratification of the latter rock I have as yet always found in a horizontal position. 



11 The green-stone slate is often approaching to green-stone ; it occurs then only 

 obscurely slaty, has a jet black color, strong glossy lustre, foliated fracture, 

 hard in a small degree ; in this state it seems here barren of metals of any kind. 

 The real green-stone slate is of a bluish black color, with small white spots of de- 

 composed felspar, half hard ; and when exposed to the air, it crumbles soon to 

 pieces, and takes a green color. The rock is reckoned one of the richest ' mo- 

 thers of ores' of any in the world. In it are found silver and copper in 

 rich beds or layers, as is the case here ; but never in veins, as in other formations*. 



" The layers of copper are of different thickness, and distances from each 

 other : the general run of the pieces of ore, constituting the layers, is two inches 

 in thickness ; but they have been found also of several feet. The pieces are in 

 general flat, as if compressed, and coated with ochre. The vertical distance be- 

 tween the layers is 4 to 8 feet, and the horizontal is even more uncertain. 



" A corroded honey-combed quartz is found in great abundance in the green- 

 stone slate, particularly along with the copper ore. It appears often on the sur- 

 face, in such places where the water has washed the earth away. It looks then 

 like indurated marl, which in other parts of the country is very common. 



" The rockf is covered with a red coarse gravel, which is the superficial soil of 

 this part of the country. In my opinion, this is formed from the decomposition 

 of the green-stone slate, and its quartzoze and ferruginous contents; for copper 

 ore is often found in it in considerable quantity, and in the same situation, as in 

 the slate rock. 



" At Yerrapillay, in a new mine, which I opened, I found two layers of ore in 

 it, at distances of four feet asunder. 



" The thickness of this stratum of gravel differs according to its situation, whe- 

 ther it is on a high or low ground. I have found it from 4 to 6 feet, and 

 more. 



" The copper ore which Dr. Thomson calls Anhydrous, the most 

 common kind, is in flat pieces, externally, of a brown ochry color ; in- 

 ternally, of a black iron color, which often passes into green ; when 

 moistened with water, it becomes almost immediately throughout green ; in some 

 places, it is bluish grey throughout. Lustre, in some places, where it is 

 black, semi-metallic ; and in the bluish grey, metallic^. The copper indeed 



* One of my specimens from Nellore is abundantly curious and interesting. It 

 consists of distinct layers of the carbonate, alternating with black micaceous schist, 

 or rather gveen-stone, affording exactly the appearance of gradual deposition from a 

 liquid at this earliest period of geological formations. The angle formed by the strata 

 of this striated rock with the horizon is stated by Mr. Kerr to be about 45°. — J. P. 



-f- See Dr. Renza's observations on veins of quartz pervading decomposed peg- 

 matite, J. A. S. iv. 42 J. — Ed. 



X This description accords so completely with that of No. 3, in the subjoined analy- 

 sis, that I have no doubt Dr. Hayne has mistaken the sulphuret for Dr. Thom- 

 son's ore.— J. P. 



