Notes on the Auriferous Slate Sf Granite Veins of N.S.W. 91 



As to the former theory, it is considered that to reach the 

 parts of the vein where the metals or ores now are, the minerals 

 must pass through a layer of cold water some hundreds of feet 

 in thickness, in which the molten or sublimed metal must at 

 once have become solid, this view will have to be abandoned as 

 impracticable. 



As to the latter theory, there is not the same impossibility 

 of its being correct, in the case of continuous veins, penetrating 

 to an unknown depth. But it will not account for the deposition 

 of metals in the detatched shallow veins, or for the bunches 

 of ores in rocks, or in flat veins, or nodules of ore in the solid 

 limestone rocks, or for the cases where the veins traverse a 

 series of distinct beds of rock, and are invariably rich or barren 

 in accordance with the character of the rock bounding the vein. 



The theory deriving the metalliferous deposits in veins from 

 the rocks bounding those veins appears to be the only satisfactory 

 explanation of the phenomena recorded, for it meets all cases 

 yet known. In support of this view we might refer to the 

 interesting experiments of Becquerel and Pox, and to the 

 repetition of the experiments of the latter by Mr. Hunt, of the 

 School of Mines, London — to the peculiarities attending the 

 deposit of lead ore in the carboniferous limestones of Derby- 

 shire and the North of England, and to the late deposits of ore 

 found in old mining works. 



This, however, only refers to the first segregation of the 

 metals from the bounding rocks, as opposed to their derivation 

 from some great deposit in the interior of our globe — after 

 aggregation the ores may in many cases have been re-arranged 

 in the veins, and where currents of water exist in veins, they 

 may have had some part in efii'ecting this re-arrangement, although 

 the cases where this is possible are not numerous. A similar 

 operation is still going on in the watered alluvial drifts, where 

 gold is being deposited, along with sulphuret of iron (iron 

 pyrites), on organic matter (such as old timber) undergoing 

 decomposition. 



The two instances of gold aggregated in bands of rock now 

 brought under the notice of the Eoyal Society clearly support 

 the above views. 



The first case is the slate vein of Cowabee, on the Murrum- 

 bidgee Eiver, which can hardly be distinguished from the 

 bounding rocks ; the latter consisting of Lower Silurian sandy 

 slates. It is a simple band of slate, nearly ' vertical, and 

 striking, with the cleavage, nearly north. At the surface the 

 band is fourteen feet wide, and at sixty feet deep it is from 

 sixteen to eighteen feet wide. When closely examined, there 

 is a slightly more mineral look in this band than there is in the 



