383 
REMARKS ON TIN ORE DEPOSITS AT MOUNT 
BISCHOFF, TASMANIA. 
By Baron Von Groppseck, Corer Mrnine Councinior 
or THE Hartz Minine Districts anp Diructor 
oF THE Royat Prusstan Acapremy or Minus at Cravs- 
THAL, GERMANY. 
Translated by G. THurnav, F.G.8., from the Special Imprint 
of the Journal of the German Geological Society of 1884. 
Read September 7th, 1885. 
The Royal Academy of Mines at Clausthal was some 
time ago placed in possession of a very fine collection of 
Australian ores. That collection was presented to our 
Academy by M. Wagenknecht, of Aachen (a Fellow of the 
Royal Society of Tasmania). 
Amongst the samples were found a number of specimens. 
of Tin Ore, together with the rocks and the minerals said to 
be associated with same, from Mt. Bischoff, Tasmania. The 
series interested me, particularly on account of a piece of 
supposed Quartz-Porphyry, which rock, it was represented, 
is associated (according to the description of 8. H. Wintle* 
and Geo. H. EF. Uirichy}) with those Tin Ores, and also because 
of some peculiar, dense, greyish-blue coloured masses. 
of mineralf which most frequently are found to enclose 
those Tim Ores. 
The chemical and microscopical tests gave the unexpected 
and interesting result, proving this Quartz-Porphyry to be a 
land of Topaz rock of porphyritic structure, the white or 
light-coloured portions of same consisting of dense Topaz,. 
whilst the greyish-blue were principally formed of dense 
Tourmalines. 
As this appears to be—so far as I am aware—a totally 
unknown occurrence of Topazes with Tourmalines carrying 
Tin Ores, a description of same may be, under the circum- 
stances, justified. As to the value of this discovery, from a. 
geological point of view, I am not able to form an opinion, 
and such can be only ascertained properly after a careful 
* §. H. Wintle; Stanniferous Deposits of Tasmania. Trans. Royal 
Society of New South Wales, 1875, vol. ix., page 87. 
+ Geo. H. F. Ulrich. Written communication; New York Book for 
Mineralogy, etc., 1877, page 494. 
+ These dense masses of minerals at first led to the belief, from the 
peculiar structure of same, that they were the results of transmuted Quartz- 
Porphyries. An analogy certainly exists in the well-known transmutation 
of Granites, carrying Tin Ores, into “Greisen” or a felspar—less rock. 
These possibilities gave rise to the now detailed researches ; and this paper 
was read by me at a meeting of the German Geological Society at Hanover 
in September, 1884. At that time I was not aware of the real character of 
the supposed Quartz-Porphyry. The special examinations of same were. 
initiated in October of the same year.—V.G, 
