OCCURRENCE OF PRECIOUS STONES IN N.S.W. 237 
notable locality for sapphire, drains an extensively denuded 
basaltic plateau. The same may be said of a place called 
Sapphire, further north of Swanbrook, 
At Berrima the sapphire is invariably found with pleonaste, so 
much so that one suspects a common matrix for the two. Now 
pleonaste can be seen in situ in basalt used as road metal about 
Kangaloon, so there is a strong presumption that the sapphire is 
also derived from the basalt. This taken in connection with the 
facts concerning sapphire at Tumberumba and in the Inverell 
districts, and the specimen of basalt with sapphire in situ settle, 
I venture to think, the question of the matrix of sapphire. 
T would add a few lines to describe the basalt containing the 
Sapphire. The specimen is waterworn but fairly fresh, as may 
be seen where a slice has been sawn off for a micro-slide. Along 
with the phenocrysts of blue sapphire there can be noted large 
crystals of a black lustrous shining mineral, which proves to be 
magnetite. Under the microscope a good deal of ferrite stains 
the slide, but the rock is on the whole apart from the presence of 
phenocrysts of magnetite, not widely different from other basalts 
in the district. The component minerals are augite, olivine, 
plagioclase, magnetite, and alteration products which sometimes 
fill cavities and show a black cross in polarised light. 
I have never seen anything to lead me to believe that topaz, 
which is so plentiful in New England, is ever found as a primary 
constituent of an igneous rock. 
The separation of the two gems has also been noted in Burma, 
and Messrs. Barrington Brown, and Judd‘ write that it is a 
noteworthy circumstance that none of the silicates combined with 
fluorine, topaz, etc., are found in the limestones that contain the 
corundum. 
The occurrence of sapphire at Bald Hill, Hill End, is very | : 
limited. All the stones found are small. 
Ores ie a a ee 
1 Report of Proceedings of Royal Society of London, No. 345, p. 392. 
