origin and mode of occurrence of gold-bearing veins. 155 



Filling of Veins. 



Having adopted the theory of lateral secretion to account for the 

 formation of most metalliferous lodes and of auriferous quartz 

 veins in particular, let us consider what action must have taken 

 place in nature to render such a theory comprehensible and 

 legitimately entitled to be taken as the most feasible method 

 of accounting for the various phenomena connected with lodes 

 and veins, Lateral secretion supposes that the following actions 

 may have taken place because they are in accordance with, 

 experiments and observed facts. 



1. That water containing carbonic acid and other solvents is 

 capable of dissolving all minerals and metals, and when the 

 temperature is high this solvent action is greatly increased. 



2. That such waters will retain these metals and minerals in 

 solution until a change of condition causes the re-deposition of all 

 or some of them, and it also affirms : — 



3. That certain, non-metallic minerals have been proved to contain 

 the metals we find in lodes and veins, and that these minerals 

 frequently occur in. the rocks which contain lodes or ore in close 

 proximity to them. 



4. That the metalliferous contents depend to a great extent upon 

 the containing country rock, and that lodes and veins are generally 

 richer in certain metals when they occur in or close to rocks that 

 are largely composed of the minerals that contain such metals. 



5. That water is capable of dissolving most if not all minerals to 

 a greater or less extent, may be taken as proved, for all natural 

 water contains some mineral in solution. It has also been ascertained 

 by actual experiment that water will act upon certain rocks and 

 clays when the conditions of pressure and temperature are varied 

 so as to effect a re-arrangement of the elements to form fresh 

 minerals, and the structure of the crystalline rocks of the granite 

 type, affords evidence that they have been transmuted or changed 

 from sedimentary rocks under the action of water at great depths 

 below the surface where the temperature would be high and the 

 pressure great. 



6. That the mineral waters of our mines even at a low tempera- 

 ture contain metals in solution is most certain, as analyses have 

 proved it to be the case, and that they deposit their metals combined 

 as minerals is also known. Organic substances are frequently 

 found silicified in our veins and alluvial leads and such minerals 

 as marcasite and siderite formed. 



It is also strongly worthy of notice that the quartz and other 

 matrices of metalliferous veins, and the metals and minerals 

 associated with them, are often found in the lodes in separate layers 

 parallel to the walls of the lode or to each other, and having all the 

 appearance of being deposited consecutively as from mineral waters. 



