OCCURRENCE OF PRECIOUS STONES IN N.S.W. 257 
As to the quality of the stone,! I venture to say, after seeing 
some hundreds of packages of it both cut and in the rough, that 
New South Wales is at the date of writing, putting on the market 
a gem that can be taken as the finest opal in the world. 
*Quite recently I spent a few days on the White Cliff opal field 
and found the output of marketable gems equal to £200 per week. 
The opal-bearing country as already stated is of Upper Cretaceous 
age. In this locality opal has been found along a strip of country 
not more than one and a half miles wide and twelve to sixteen 
miles long. | 
*Some of the best finds were made by following surface indica- 
tion where some opal was left by the weathering of the sandstones, 
but as a rule, miners sink shafts anywhere within the area indi- 
cated with the hope of finding a seam of opal. Even within this 
area, experience has shown the probabilities of finding good stone 
is confined to certain localities, that show no specially distinctive 
features, ; 
*When on good ground the opal is not confined to a single level. 
T saw opal at three separate levels in one shaft. In one of these 
drives, two horizontal layers of opal could be seen connected by 
@ vertical film-like sheet of the same material. In Block 1, seams 
of opal were found at depths of fifteen and twenty-seven feet from 
the surface, and similar conditions can be observed on other parts 
of the field. The question then arises, as to the probability of 
opal being found to considerable depths on the field. Present 
appearances would appear to indicate that the conditions under 
which the opal is found cease at a depth of from fifty to sixty feet 
from the surface. The stratified zone in which the opals occur 
cannot be described as a sandstone. Mr. Jaquet refers to it as a 
Kaolin. In my opinion, the term marl-stone would be more 
’ppropriate. There is no doubt about the matrix being felspathic, 
and much of it contains sufficient carbonate of lime to eflervesce 
DS eerenagreree rc aE IER 
a A remarkable black opal is sometimes found and is valued as a curio. 
‘is when polished a perfect black, and when, as it often happens, it is 
Seamed with white opal, a very pleasing effect is obtained. 
Q—Oct. 7, 1896, 
