Notes on the Auriferous Slate Sf Granite Veins qfJST.S.W. 93 



In the above case, we have an aggregation of gold and 

 sulphurets of iron on bands of rock, — these bands having, no 

 doubt undergone partial decomposition at certain points ; but 

 still they are distinct bands of rock, not segregated from the 

 granite, or injected into fissures in that rock, but a portion of it, 

 something quite distinct from a mineral vein. 



There is the same difiiculty in accounting for this deposit of 

 gold and iron ore that is felt in the case of the auriferous slate 

 bands, unless it is referred to segregations from the bounding 

 rocks. It, however, brings out in a more striking light the 

 action of the force which, causing change and decomposition in 

 a homogeneous mass of rock, on lines running parallel to each, 

 other over a large area, at the same time has aggregated on the 

 lines thus formed the gold and iron ore previously scattered 

 throughout the whole mass of rock. Auriferous granite bands 

 are stated to exist in South America ; but this is the first 

 example of the kind known to me to occur in Australia. 



The endeavours made to bring science to bear on practical 

 mining have not hitherto been attended with much success, 

 mainly because the views promulgated were formed in the closet 

 by persons imperfectly acquainted with the facts. If real 

 progress has to be made, the first step must be the careful 

 collection and registration of the phenomena observed, and as 

 these accumulate, the deductions drawn will be tested with 

 greater certainty. At present we must, in a great measure, 

 depend on empirical knowledge in mining afi'airs, using the hints 

 obtained from scientific inquiry as aids, rather than as guides. 

 The rough outline given in this paper indicates how much has 

 yet to be investigated and explained ; and it may take many 

 years of combined labour before the subject is so thoroughly 

 understood as to allow of its application to practical work ; but 

 that this will in the end be attained, we may rest assured. 



Note. — The Eev. W. B. Clarke, in his •' Eeports on the 

 Southern Gold-fields," calls attention (at page 58) to the 

 existence of gold in granite, and explains how it has been held 

 enclosed in sulphuret of iron, and liberated by the decomposition 

 of the iron ore. The bands of auriferous granite now opened 

 entirely confirm these views, with the exception that instead of 

 the deposit being confined to the outer surface of the granite 

 it is in vertical bands of rock, on which the auriferous pyrites 

 has been aggregated. In the same district, however, there are 

 large masses of granite rock impregnated wath pyrites (far 

 more sparingly than in the bands,) in which the oxidation of 

 the sulphurets, and the consequent liberation of the contained 

 gold, is continually going on near the surface of the rock. 



