1869.] LE NEVE FOSTEE CAEATAL GOLD-FIELD. 337 



It was only on the north side of the Yuruari, near the Tupuquen 

 Pord and north of Callao, that I noticed outcrops of a rock which 

 I have called " gabbro " on the authority of Mr. David Porbes, F.E.S. 



To the north of the mining district-— in fact, in the country about 

 IJpata, gneiss, mica-schist, hornblende-schist, and granite occur; 

 but time did not permit my making any full examination of this 

 part. It will thus be seen that to the west and north the gold-bearing 

 slates are surrounded by gneiss and other metamorphic rocks. No 

 fossils have as yet been found, though carefully searched for by Dr. 

 Plassard ever since he discovered the gold-fields. The age of the 

 rocks is consequently unknown. 



I will now pass on to the gold deposits of the Caratal district. 



These may be classed under four heads : — 1. Lodes, veins, " reefs," 

 or " ledges," j^Zones ; 2. Alluvial or "placer" diggings, or greda ; 

 3. Hed earth, or tierra clejlor; 4. Gravel and sand of river-beds. 



1. Lodes. — About a dozen lodes have been discovered and worked 

 on. It is impossible to give any general direction of the strike and 

 dip of these lodes ; but it may be remarked that several well-marked 

 and rich lodes run east and west, while others, equally productive, 

 have strikes approaching to north and south. 



As the lodes are few in number, a short description of each will 

 furnish the easiest method of giving an idea of their general nature. 



The Callao lode lies about a mile and three-quarters N.N.W. of 

 Nueva Providencia. It is a north and south lode dipping west, and 

 is from 1 foot to 2 feet thick in many places ; it consists mainly of 

 quartz with a little iron-pyrites and brown oxide of iron, &c., and a 

 few blackish streaks due, perhaps, to chlorite. The gold in this lode 

 is very coarse, and specimens of pure white quartz and native gold, 

 without a particle of oxide' of iron, are often found. The surrounding 

 rock or *' country," is felstone, with a little iron pyrites. The 

 miners say that the presence of iron pyrites is a favourable sig-n for the 

 productiveness of the lode. The Callao lode has been worked along 

 the strike for a distance of about 200 yards, and it is said to die 

 out southwards. The deepest workings in the Caratal district are 

 upon this lode ; but they only reach down 36 yards, further pro- 

 gress being prevented by water and the want of pumping-ma- 

 chinery. Yery large quantities of gold (I believe I am under the 

 mark in saying 1000 oz. per month) have been obtained from 

 CaUao. 



The Corinna lode is situated further eastward, on the bank of the 

 Yuruari. The lode is 4 feet wide in places, and dips west. It 

 consists mainly of quartz, with brown oxide of iron, mammiUated 

 pyrolusite, thin streaks of a blackish mineral, and visible gold. 

 This lode has been worked to a depth of about a dozen yards and 

 has been profitable. 



In the neighbourhood of the Corinna the American Company has 

 made openings upon other lodes and branches. Some of the quartz 

 shows visible gold, the rest does not ; but all is auriferous ; on an 

 average, I am told that the quartz from these openings gives about 

 1^ oz. of gold to the ton. The "country" of these lodes and of 



