1872.] DAINTREE GEOLOGY OF QUEENSLAND. 307 



An analysis of this Paddy's-Gully felsite afforded me : — 



Silica ,. 70-800 



Alumina 19-186 



Ferric oxide 1-164 



Magnesia 0-827 



Potash 1-826 



Soda 1-208 



Water, constitution 3-250 



Water, hygroscopic 1-425 



99-686 



The appearance of the rock is that of a partially decomposed 

 felsite or trachyte, in which a portion of the alkali of the felspar has 

 been replaced by water, and kaolin formed, as has no doubt been 

 the case. 



The peroxide of iron is evidently the representative of pyrites, as 

 it partially fills cubical cavities in the decomposed rock, and forms 

 no portion of a silicate. 



Though the probabilities all tend to the assumption that this 

 felsite was the absolute matrix of the gold found in the ravines 

 which intersect it, still we are not able to make the definite asser- 

 tion, not possessing sufficient material to concentrate the heavier 

 particles by crushing, washing, and determining the presence of 

 gold by assay. In rock of the same character, however, in another 

 portion of the same gold-field, this fact is beyond a doubt. 



At the Upper Cape diggings are two so-called reefs, viz. " Green's " 

 and " The Tunnel," which are of the same material, and of which 

 many tons were crushed, with a yield of from 6 to 8 dwts. of gold 

 per ton, and an unlimited supply of material. 



The analysis of this stone aflibrded me : — 



SiUca . 74-000 



Alumina 16-137 



Ferric oxide 0-963 



Magnesia 0-627 



Potash 3-791 



Soda 0-987 



Water, constitution 0-750 



Water, hygroscopic 2-650 



99-905 



Specific gravity 2-451. 



This was really a dyke of felsite, differing, as will be seen, very 

 little in composition from that of Paddy's Gully ; but the decompo- 

 sition of the felspar had not preceded so far into the kaolin element. 



The section in the tunnel by which the " Tunnel reef" was 

 worked, is here sketched (Fig. 17). 



As neither of these paid the working-expenses, they were aban- 

 doned, and now remain unworked. 



In the neighbourhood of Rockhampton, at the so-called " Cum- 



