IX AU GIT UAL ADDRESS. 
mineral and metallic salts in the water in the fissure and the adjacent 
rocks would be decomposed, and the constituents deposited as bases, 
such as gold and silver, or as compounds, such as quartz, calespar, and 
sulphide of iron, all which were in course of deposit at the same time* 
as the angles of the crystals cut into each other. The theory of 
thermal springs is contra-indicated as the lime appears as calespar, a 
form occurring in cold solutions, and not in the form of aragonite as 
in’hot solutions. There have been many speculations as to the sources 
from which the gold was derived, but that which best accords with the 
actual conditions is that the metal exists in very minute quantities in 
the mass of the adjacent rocks, from which it has been transferred 
through the agency of electric currents and the solvent action of 
alkaline chlorides, which dissolve small quantities of the precious- 
metals, and would be subject to decomposition at the places where 
fissures caused greater resistance to the electric current. One 
remarkable circumstance is that the character of the rocks forming 
the sides of the fissures has an evident influence on the richness of 
the ores in metal; where lime, magnesia, or other alkaline compounds, 
or graphite enter into their composition, the gold especially is more 
abundant than where the rocks contain silica and alumina only. 
QUEENSLAND’S GOLD MINES. 
In Queensland, Gfyrnpie affords some instructive examples of 
fissure lodes. In some, large masses of rock have fallen into the 
fissure before the ore was deposited, and have formed what miners 
term “ horses,” where the lode splits into two thin sheets to again 
unite below the fallen mass. The Mount Morgan mine may also be 
cited as a case where several fissure lodes rise to the surface in close 
proximity. The ore was originally an auriferous pyrites, but the 
sulphide of iron was largely decomposed, leaving the gold disseminated 
through the oxide of iron. In other cases the sulphur and iron have 
both been dissolved out, and left cellular quartz, with gold in the 
cavities or as fragments of gold, mixed with minute crystals of quartz, 
presenting the aspect of kaolin, for which it has been mistaken. 
The auriferous deposits, which occur in the intrusive granites, 
appear under conditions differing from the true lodes in sedimentary 
rocks, as the intrusive granitoid rock forms dykes which fill fissures in 
the older true granites, and also cut through the sedimentary slates. 
It bears evidence of intrusion in a state of fusion, or, at least, in plastic 
condition, and has subsequently crystallised, after which there has 
been shrinkage, causing cavities, as the sides of the dyke were held in 
position by the enclosing rock. The vertical shrinkage being greater 
than the horizontal, the cavities were nearer the horizontal than the 
vertical, and being afterwards filled with ore formed what are called 
“floors,” one characteristic of which is the tendency to lenticular 
form, or a central maximum thickness with thinner edges. The 
