ORES OF COPPER 
R7 
higher parts of the lode now destroyed or may be due to 
Primary deposition. ] 
The copper-field is about 80 miles long and includes, ac- 
tording to Finlayson (Econ. Geal., v, 1910, p. 407), thirty- 
three chief ore-bodies. The South Lode of Rio Tinto and its 
continuation, the San Dionisio Lode, are together more than 
I} miles long. La Zarza Lode and its continuation Perrunal 
are together also 1} miles long, and their full length is not yet 
known. La Rosa and the Sotiel are 11 50 and 900 yards long 
Tespectively, Most of the ore-bodies are between 250 and 
000 yards long. The San Dionisio is 
800 feet wide, and most of the larger 
lodes are between 150 and 500 feet wide. 
Their depth is small ‘in relation to 
their thickness, According to Finlayson 
the depth probably in no case exceeded 
about 3000 feet, and seldom 1500 feet. 
Some of the ore-bodies are thicker be- 
low, as the upper part of the lenticle is 
%ill preserved.” The ore-bodies eceur in 
different rocks, According to Finlay- 
son’s list four of them are in porphyry; 
two at the junction of slate and dia- 
base; eleven at that of slate and 
Porphyry, as at Rio Tinto and Calanas 
and sixteen are wholly enclosed in sedi- 
Qentary rocks, such as the Tharsis, 
Sotiel, and El Tinto (Fig, 20) which are 
In slate, 
Mr. Lyra similar mass of copper- oo 
bearing pyrite occurs at the Mt. Lyell Mine in Western 
Tasmania,” 50 miles inland, N. of Macquarie Harbour. 
Alluvia] gold was found in the district in 1881 and at Mt. 
Lyell in 1383 ; in 1891 was found the *“ Iron Blow,” a gossan 
Which contained gold and silver, and covered a large ore- 
body of Pyrite containing sufficient copper to pay for mining, 
the gold and silver being recovered as bye-products. 
The Mt. Lyell Mines? occur close to the contact of the 
YJ. W. Gre « os " : vis 
: gory, “The Mt, Lyell Mining Field with other Pyritic 
Ore Bodies,» Austral. 7M.E., 1905, viii. . 198.