10 PROCEEDINGS OP THE GEOLOGICAL SOCIETY. [XoV. 6, 



The underlying rock of the principal part of the area consists of 

 the black flinty rnetamorphic slate before noticed ; but dispersed 

 through it are several small outcrops of a rather coarse-grained 

 micaceous granite enclosing large radiating patches of " schorl ; " 

 and close to one of these granite protrusions several veins of solid 

 tin-ore, from 1 to 4 inches thick, have been found traversing the 

 slate rock. These veins lie about ^ mile away from the granite 

 exposed in the creek. The ore broken from these is, if any thing, 

 of a more solid character than the vein-ore of the Elsmore mine, 

 druse-cavities being apparently very rare or quite absent. That 

 these veins contributed by their denudation largely to the tin-ore 

 distributed through the surface detritus and alluvial drift near and 

 below their line, there can be no doubt ; but taking into account that 

 both the latter are rich in tin-ore a considerable distance higher up 

 the hilly plateau, and that specimens of quartz with crystallized tin- 

 ore attached have been found there, it is not less certain that such 

 ore and specimens must have been derived from other tin-ore veins 

 traversing the slate, or perhaps a peculiar rock which occurs in large 

 dykes and patches here and there over the area. This rock repre- 

 sents an extremely hard and tough greenstone diabase, the augitic 

 constituent of which has the cleavage and lustre of diallage. I did 

 not myself see specimens ; but a miner in charge of the ground aver- 

 red that he had found pieces of the rock traversed by thin veins of tin- 

 ore. Its contact, or mode of connexion with the granite, could not 

 be observed anywhere, the nearest protrusions of the latter lying 

 perhaps 6 chains off. However, as the granite, judging from its scat- 

 tered outcrops at the place and its massive occurrence about half a mile 

 northward, doubtless underlies the country all round, it is most likely 

 that the greenstone, as the younger of the two, has broken through it. 

 A peculiarity of the latter is, that it weathers black or brownish black, 

 and is far harder and tougher where exposed at the surface than 

 underneath a covering of detritus or alluvial drift. At places where 

 it is strongly affected by decomposition, as, for instance, in some of the 

 holes sunk in the small gullies, in which it forms the bottom, it 

 much resembles certain varieties of Serpentine. 



The washing on a large scale of the stanniferous detritus and 

 alluvial drift of the area under notice can most profitably be exe- 

 cuted only by ground-sluicing ; but the conducting of the water by 

 means of races to the place, or forcing it from the creek for a dis- 

 tance of about a mile to the top of the range, a height of nearly 300 ft., 

 will be rather expensive and difficult ; still the richness and extent 

 of the ground would warrant the undertaking. 



Positive want of water or too great an expense attached to the 

 bringing of it to the stanniferous localities will, however, I am afraid, 

 be prohibitory of the working of a great number of those recently 

 discovered. Still the produce of such as can be worked* will 

 doubtless in no long time sensibly affect the tin-markets of the 

 world : in fact it seems not unlikely that the production of tin- 



* The Quart-pot Creek, in Queensland, will, it is supposed, alone yield from 4 

 to 500 tons of ore per week. 



