OCCURRENCE OF PRECIOUS STONES IN N.S.W. 245 
prietary Mine, Emmaville, beautifully lustrous crystals are found 
associated with topaz, fluorspar, biotite, and quartz and enclosing 
crystals of arsenical pyrites. At the same mine a massive rock 
composed of topaz crystals held together by a white kaolin is 
common. Professor David records the occurrence of this rock in 
his report on the emerald mine.! At the time of Professor 
David’s visit this topaz rock formed a vein eight inches thick. 
Since then very much wider masses of almost pure topaz rock 
have been broken down at this mine. The surface lustre of some 
of these crystals is extremely brilliant, and without exception they 
are clear and colourless but flawed across the prism. 
Forms.—Crystals of a more robust habit are found at Oban. 
The Emmaville topaz from the matrix frequently shows the basal 
pinacoid pyramid end prisms well developed. The Oban crystals 
have a wedge-shaped appearance that the topaz at the Emerald 
Proprietary Mine never show. This wedge shape is due to the 
greater development of the brachydomes. The face y of Dana’s 
System of Mineralogy is generally present modifying /. The : 
prisms 7 and m are usually striated. MM is occasionally present. 
In one specimen a cleavage to parallel f was very clearly shown. 
The basal cleavage is as always very well developed. 
The largest crystal I have seen is the example figured on Plate 
13, fig. 3. This weighed a little over sixteen ounces when fou nd, 
It was discovered in a granitic detritus at Oban in New England. 
The topaz reproduced on Plate 1 3, figs. 1 and 2, are also from the 
Oban district. The waterworn example is a perfectly clear white 
stone weighing a little over seven ounces, and from which a gem 
could be cut to rival the famous Maxwell-Stuart stone. Fig. 2 
On the same plate is an imperfect crystal from Oban with a 
slightly greenish cast. *The rounded stone shown in fig. 1 being 
perfectly clear I determined its specific gravity. 
Specific gravity of a New England topaz weighing 
203°548 grams at 60° F.... 3-573. 
1 Annual Report of the Department of Mines, N. S. Wales, 1891, p. 230. 
