122 TRANSACTIONS OF THE CANADIAN INSTITUTE. [VOL. II. 



Galenas occurring in the older crystalline metamorphic rocks are more 

 auriferous and argentiferous and continue to a greater depth than those 

 occurring in limestone, for instance, the galena from the mountain 

 limestone of Cumberland, Derbyshire, etc., although it contains silver is 

 not to be compared with that from Devon or Cornwall, which occurs in 

 metamorphic clayslates or killas ; formerly some of the veins in Corn- 

 wall produced from 80 to 140 ozs. of silver per ton of ore. 



Philips gives in 1874, the statistics as 4,098 tons of lead containing 

 207,700 ozs. of silver for Devonshire. Before proceeding further, I may 

 say that there is not in existence either galena or iron pyrites in which 

 either gold or silver does not exist. I should mention that I would 

 have incorporated the results of a number of tests made by me for those 

 metals in both these minerals, but Percy has in his Metallurgy of Lead 

 a table, which shows the results of his research in this direction which I 

 do not propose to improve on. When I speak of the presence of these 

 metals, they may either be there as mere traces or may be in such large 

 proportion as to warrant their working ; for instance Philips makes 

 mention of the Morro Velho Mine in the province of Minas Geraes, in 

 Brazil, as being the largest and most prosperous in that country up to 

 the year 1863, it having produced since the year 1839, a net profit of 

 one million sterling to its proprietors, but at that time was stopped by 

 the combustion of the timber w^ork, supposed to have originated from 

 the oxidation of pyrites, the workings being on auriferous pyrites. At 

 the present time, quite a portion of the annual production of gold is 

 obtained from pyrites. Veins of pyrites are generally oxidised to a 

 great depth, although in some places they are found normal with merely 

 a surface oxidation ; the results are generally Ferric Oxide, Fe^ O.j. 

 Hydrogen Sulphides, H, S, and Sulphur Dioxides SO„, the excess of 

 these products of oxidation is carried away by circulating surface or 

 subterranean waters, and leaves with the matrix some of the ferric 

 oxide and the greater part of the gold. A good illustration of those 

 facts is the Mount Morgan Gold Mine in Australia, where the ore, if it 

 may be so called, is a siliceous sinter containing gold in a very finely 

 divided state, which has resulted from the oxidation of pyrites, which is 

 proved by the matrix being a siliceous sinter, as the intersticial or 

 honeycombed appearance of same is due to the crystals of pyrites which 

 once filled same having oxidized. In the Lake of the Woods, in 

 Ontario district, especially on the margin of the lake and also in the 

 lake itself, there is a ferruginous earth, which contains considerable gold 

 and which is said to exist in considerable quantities. The gold exists 

 as nuggets as well as in a finely divided state, this also, I believe, has 

 originated from the decomposition of iron pyrites. 



