78 
portions of this rock, which weathers hrown and becomes argillaceous, though main- 
taining its compactness, that the quartz veins traversing it are found to be so highly 
productive. In its ordinary condition it is excessively hard and is the most formidable 
obstacle the miners have to contend with, some from the very surface, and others at 
varying but at comjiaratively shallow depths.’* And further on in the same report he 
gays : — ‘ Up to the present time scarcely any of the reefs have been opened up to a 
greater depth than between 60 and 70 feet, and but little stone has been raised below 
30 or 40 feet within the limits of the belt of greenstone to which 1 have before referred. 
From the crystalline character and extreme hardness of this rock, which I do not think 
is likely to become softer as it is followed downwards, there is little probability that the 
reefs traversing it can he profitably mined to any great depth, in fact in one or two 
cases the tendency to become naiTowed, and impoverished also, is already apparent ; and 
though, perhaps, they may not be altogether “ pinched out,” the quartz veins will, 
doubtless, become so attenuated that it will be no longer profitable to work them.’ 
“ Mr. Aplin’s remarks with reference to the unjrroductiveness of the reefs in the 
‘ greenstone’t have been fully borne out by later experience, since none of the reefs 
contain payable, if any, gold at all, when passing through it. The mistake he made was 
coming to the conclusion, without sufficient evidence, that the greenstone was in the 
form of ‘ an irregular-shaped mass or broad dyke,’ whereas future development has 
^n-oved it to be in the form of an intrusive ‘ sheet.’ Had it existed as a dyke or 
irregular mass, one would have expected it to extend to any depth that the miner could 
have reached, and it would have been useless to have attempted to' follow the reefs into 
it. The miner, in the early days, abandoned the reefs as soon as the greenstone was 
reached, and ho added also to his difficulty by calling every rock ‘greenstone’ which 
was of a green colour. 
“ It was not for some years, when the upper levels were nearly worked out, that 
deeper sinking was, at last, resorted to, and that auriferous bods were found lying 
beneath the greenstone. In the case of an igneous rock, such as this, intruded in the 
form of a ‘ sheet,’ parallel with the planes of bedding, there is no reason why beds 
favourable to the occurrence of gold should not exist below as well as above it. The 
greenstone is intimately associated with other rocks which are, undoubtedly, of sedi- 
mentary origin, but which have by alteration become so semi-crystalline that it is at times 
difficult to distinguish between them. 
“ Doubts have been expressed as to whether the greenstone is an igneous rock at 
all ; however, from its relation to the surrounding rocks, and the baked appearance some 
of the rocks in contact with it have, there can bo little doubt but that it is of igneous 
origin, and that it is an intrusive sheet which, while generally conforming to the bedding 
of the rocks, at times, both at its upper and under surfaces, break across their planes of 
bedding. This feature can be well seen in the Smithfield United and the No. 5 North 
Glaninire Claims. The ‘ greenstone’ varies from a dark to a cabbage-green in colour ; 
it is very hard and breaks with a somewhat conchoidal fracture. In the microscope, 
crystals of i^lagioclasc felspar are discernible ; also very much altered greenish crystals, 
either altered hornblende or augite, changing into viridite ; opaque crystals of iron 
pyrites and small grains of magnetite. The rock has undergone too much alteration to 
name it definitely. It was probably either a diorite or dolerite. 
* Report from the Government Geologi.st for South Queensland on the Geological and Mining 
Features of the Gympio Gold Field. Brisbane : by Authority : '18(58. 
t Mr. Rands seems to have misunderstood Mr. ApUn’s remarlcs, which distinctly imply that the reefs, 
so far from being unproductive, were most ijroductive when traversing the greenstone, or at least its 
decomposed portion. Mr, Aplin, however, was greatly in en'or as to the fact. (B.L.J.) 
