Gold 303 



contain gold. It is inferred that the majority of veins have 

 been formed by such waters. Lodes are formed whenever 

 circulating waters act as solvents in one part of their course 

 and as precipitants in another. Gold-bearing veins have been 

 found in rocks of all compositions and of all geologic ages. 

 Lodes, which are mainly the result of cavity fillings, are more 

 likely to occur in rocks which break easily, producing cavities, 



FIG. 85. Ore face in Malvina mine showing typical ribbon vein structure. 



such rocks as slates and schists, or in rocks which are so hard 

 that when fractured the cavities will remain open giving cir- 

 culating solutions a good chance as granites and gneisses. 



Lodes Formed from Solutions 

 Deep in the Earth 



After extensive gold deposition in pre-Cambrian time there 

 has been no widespread formation of gold-bearing lodes until 

 late Tertiary time. Theoretically a lode is a vein of mineral 

 matter that fills a space formed by the fracture of the rocks, or 

 a space from which some other mineral or minerals have been 



