OCCURRENCE OF PRECIOUS STONES IN N.S.W. 271 
Plate XX. 
Fig. 1—Highly inclined Silurian slates Sturt’s Depdt Glen, N.S. Wales 
The principal ay vaginal in the west ae sessile fas gst ae are 
opals and garn These coun 
respectively. ne plate shews the contrast presented by Silurian a 
Cretaceous country. 
Fig. 2—Cretaceous escarpment between Tinaroo and Tibooburra, N. S. 
Wales. 
Nore—* Paragraphs or sentences preceded by an asterisk have been 
added since the reading of the paper. 
Discussion. 
Mr. Henry G. Suiru, said :—Mr. President, I would like to 
make a few remarks on portions of this paper, as there are certain 
Statements contained therein that should not go unchallenged, 
and that are certainly open to criticism. I may mention that the 
time to prepare my notes has been very short, as the copy of the 
paper only came to hand this morning. First, under the section 
fuby, the statement is made that “The best stone from these 
drifts was in the possession of Mr. Milner Stephen. It weighed 
within a fraction of one carat, was perfect in colour, but showed 
a feather on the templet.” Mr. Stephen’s collection of gem stones 
is now the property of the Government of New South Wales, 
having passed into the possession of the Technological Museum. 
In my capacity as Mineralogist to that Institution, the duty of 
determining the accuracy of the naming of the specimens in that 
collection, has devolved upon me. In it was a cut stone from 
this locality (near Mudgee), said to be a ruby, weighing over one 
carat, and which stone I presume is the one referred to in the 
paper. This was found on investigation not to be a ruby, but a 
topaz. In colour it resembles the burnt topaz, obtained by heating 
the dark wine-coloured topaz of South America, it has a specific 
gravity of 3-51 and its hardness is 8, it being readily scratched 
‘by a sapphire. The methods whereby gem stones are determined 
to-day, are perhaps, more accurate than those in use when Mr. 
Stephen's Specimens were named, but the question arises whether 
