156 NOTES. 
deposits, but I am unable to obtain sufficient data to tabu- 
late or compare to any great extent the cases in which 
these are associated. 
In a paper by Baron Von Groddeck, chief mining 
councillor of the Hartz Mining District (translated by 
Mr. G. Thureau, F.G.S.), on the tin ore deposits at Mount 
Bischoff, Tasmania, read before Royal Society, Tasmania, 
in September, 1885,* the baron draws attention to a kind of 
topaz rock of porphyritic structure, the white or light-coloured 
portions of the same consisting of dense topaz, whilst 
the greyish-blue were principally formed of dense tourma- 
lines. The author, after mentioning that former reporters 
have considered the tin lodes to be enclosed by quartz 
porphyry, goes on to say: “If it has now been unmistakably 
proved that that specimen is actually not quartz porphyry, 
but a porphyritic topaz rock, then the question arises 
whether any such quartz porphyry occurs at Mount Bis- 
choff at all, and whether the whole formation, assumed to 
be such rock, is not very probably a topaz rock, and in what 
manner, and under what conditions the latter occurs 
contiguously to the real quartz porphyry.” 
I have drawn somewhat at length from this article, as, 
given that it is a topaz rock, it is probably the most 
important of the associations of topaz and tin stone. 
Tin ore is usually met with in veins traversing granite, 
mica-schist, gneiss, chlorite or clay slate, and porphyry, 
and is associated with topaz in Cornwall; at Schlackenwald 
and Zinnwald, Germany; at Durango and Guanaxuato, 
Mexico ; and, to come nearer to us, traversing the eurite 
and greisen granites near Elsmore, N.S.W. Granite and 
gneiss also are the usual repositories of topaz. 
J. A Phillips, in his work on “ Deposits,” says that M. 
Daubrée, some forty years ago, first called attention to the 
fact that, with the exception of quartz, the minerals most 
constantly associated with tin ore are compounds containing 
fluorine, principally fluorsilicates, such as lepidolite and 
topaz; sometimes also fluorphosphates and fluorides, the 
latter being present chiefly as fluorspar. Boron is a con- 
* “ Remarks on Tin Ore Deposits at Mount Bischoff, Tasmania.” Pap. 
and Proc. R. Soc. of Tasm., 1885, pp. 388-394. 
