C. GOULD ON A RECENT DISCOVERT OF TIN-ORE IN TASMANIA. 109 



6. Note upon a Eecent Discovert of Tin-ore in Tasmania. By 

 Charles Gould, Esq., B.A., F.G.S. (Read June 24, 1874.) 



As a sequel to discoveries of tin-ore in abundance made during the 

 last two years in Queensland and New South Wales, there has been 

 one of some importance recently in Tasmania, which has this special 

 interest, that the ore has been found in large masses in situ, and 

 that the containing rock is lithologically distinct from the ordinary 

 ternary granite which forms the whole of the stanniferous country 

 of Queensland, and, so far as my information extends, of New South 

 Wales. 



The tin-stone also has an individuality of character not shared by 

 that in the adjacent colonies, occurring in several distinct varieties 

 of form within the distance of a few chains. 



I forward a small series of samples for the inspection of the Mem- 

 bers of the Society, among which I would specially invite attention 

 to a fragment from a large mass (itself 80 lbs. in weight) which 

 has an appearance on fracture sufficiently approaching to that of a 

 haematite to deceive a casual observer. 



This discovery of tin- ore has been made at Mount Bischoff, in the 

 N.W. portion of Tasmania. Active operations were only com- 

 mencing when I visited the spot ; and in the absence of mining 

 experience on the part of those engaged, coupled with the numerous 

 obstacles to the progress of pioneers, presented by a rough and 

 exceptionally difficult country, some time may be expected to elapse 

 before its full importance is developed. 



Mount Bischoff is distant by the present route fifty-four miles from 

 the place of shipment ; and while its vicinity generally is covered with 

 thick forests of myrtle (Fagus Cunninghamii) , the summit itself 

 (where the tin occurs) is so densely shrouded by an almost impe- 

 netrable scrub of Anodopetalum biglandulosum (" horizontal scrub " 

 of the colonists) that any estimate of the exposed area of stanni- 

 ferous rock is impossible at present. It does not appear to exceed 

 a few hundred acres. 



Mount Bischoff is a conical eminence, rising to about 2500 feet 

 above the level of the sea, perched on the western edge of the great 

 basaltic plateau of the Surrey Hills, the average elevation of the lat- 

 ter being probably a little over 2000 feet. 



It consists of a small protrusion of a porphyritic rock having a 

 felsitic base, with granules and crystals of quartz and felspar ; it 

 weathers white, and is honeycombed or vesicular on the surface, 

 most probably from the decomposition and removal of pyrites, which 

 is freely disseminated throughout in places. 



The western and southern flanks expose uplifted contorted 

 schists, and metamorphosed formations, among which I noted traces 

 of conglomerates belonging to the lowest of the sedimentary deposits 

 in Western Tasmania. 



