OCCURRENCE OF PRECIOUS STONES IN N.S.W. 265. 
districts. There is reason to believe that basalt is the matrix of 
sapphire. The blue sapphire is abundant under the conditions 
mentioned. The bulk of the stones found are opaque, and stones 
of good quality are rare. Some bronze coloured and yellow 
Opaque sapphire from the Berrima district are remarkable for 
their high specific gravity. The-ruby is in New South Wales the 
rarest of our gems. 
Emerald—Emeralds are found near Emmaville in a felsitic 
matrix associated with topaz, fluorspar, and tinstone. Emerald 
and beryl occur in the same district in a granitic matrix. 
Topaz—Topaz of excellent quality is found in New South 
Wales. It occurs for the most part in the tin-bearing granites 
of the northern portion of the colony, and has been discovered 
in situ, but more abundantly in the tin-bearing drifts and recent 
detrital deposits. 
Opal—Opal of excellent quality is found in Cretaceous beds in 
Western New South Wales, This opal is found to replace shells, 
belemnites and saurian bones of Cretaceous age. ‘The silica for 
this opal has been derived from beds of organic origin-—diatom- 
aceous or radiolarian. Opal is also known to fill the cavities in 
lavas, the silica of these gems being derived from the decompo- 
sition of the felspars. 
Other Gems—Zircon is abundant in a few localities, and in 
lesser quantity is to be found in drifts over granitic and lower 
Palzozoic areas. Garnets are abundantly distributed, but stones 
that may rank as gems are known from a few districts only. — 
From a scientific standpoint it will be seen that the variety of 
our known gem-stones is sufficient to attract attention, and 
open up a subject worthy of more elaborate research. From a 
commercial point of view we may easily believe that the gems, 
and precious stones of the Colony form not an inconsiderable item 
amongst the factors that go to make up the grand total of the 
Colony ’s magnificent heritage—her mineral resources. 
