ORIGIN AND MODE OF OCCURRENCE OF GOLD-BEARING VEINS. 151 



6. Molecular aggregation. 



7. Electrical currents. 



The theory of igneous injection supposes that the quartz or other 

 matrix of the veins or lodes together with the contained metals or 

 minerals has been forced into fissures, cracks or cavities, caused in 

 most cases by the same igneous force that injected the vein matter 

 and that these having become solidified in the fissures, the lodes 

 were thus formed. It therefore supposes the formation of veins 

 and lodes to have taken place very rapidly and in close proximity 

 to violent volcanic disturbance. 



The sublimation theory considers that vein fissures were filled 

 by the condensation of volatilized metals and minerals derived from 

 some portion of the interior of the earth where intense heat 

 prevailed. 



The advocates of the aqueous ascension theory argue that the 

 mineral waters containing the metals in solution have risen in 

 fissures or cracks in the earth, and precipitated their contents 

 upon the walls or sides of these fissures, (and in any cavities they 

 could obtain access to) until they were almost or entirely filled 

 with lode matter. 



Those who support the aqueous solution theory believe that all 

 the contents of mineral lodes were washed in from above. 



Lateral secretion accounts for the formation of most veins and 

 lodes by stating that the rock enclosing the lodes contains in itself 

 nearly or all th,e constituents of the veins, and that these have 

 gradually accumulated in the lodes in consequence of water 

 dissolving various minerals and metals from the country rock, and 

 then after filtering through the walls of the fissure redepositing all 

 or some of them. 



Molecular aggregation considers that the minerals and metals 

 of the veins have collected together in a somewhat similar manner 

 to that in which minerals collect together in the crystalline rocks, 

 for instance like pegmatite in granite and the concentric layers in 

 orbicular diorite. 



Those who support the electrical hypothesis, say that both the 

 formation of the fissures and the collection of the minerals in them 

 could be produced by electrical action. 



The advocates of each of these several theories have proved to 

 a certain extent the possibility of veins of minerals being formed 

 in accordance with their views, and interesting have been the 

 experiments made to support their arguments. Magnetite for 

 instance has been formed by sublimation in reverberatory furnaces 

 as well as in volcanic fissures, and Daubree succeeded with the 

 aid of nourine in forming tin ore, oxide of titanium, and quartz by 

 sublimation. Durocher passed gases and metallic vapours into 

 heated glass tubes and obtained crystals of blende, iron pyrites, 



