570 Reports and Proceedings — 



The workings of the Elsmore Company, situated on the north- 

 west side of the Macintyre river, about twelve miles E. of the town- 

 ship of Inverell, include a granite range about 250 feet in height 

 and nearly two miles in length. The granite of the range is micaceous, 

 with crystals of white orthoclase, and is traversed by quartz-veins 

 which contain cassiterite in fine druses, seams, and scattered crystals, 

 and by dykes of a softer granite, consisting chiefly of mica, and with 

 scarcely any quartz, in which cassiterite is distributed in crystals, 

 nests, and bunches, and also in irregular veins of several inches 

 in thickness. This granite yields lumps of pure ore up to at least 

 60 lbs. in weight. The quartz-veins contain micaceous portions 

 which resemble the "Greisen" of the Saxon tin-mines. The deepest 

 shaft sunk in one of the quartz-veins was about 60 feet in depth. 

 The author noticed certain minerals found in association with the 

 tin-ore, and the peculiarities of the crystalline forms presented by 

 the latter. 



The drift is very rich, and consists of a generally distributed 

 recent granitic detritus, from 6 in. to 2 ft. thick, and of an older 

 drift (probably Pliocene) capping the top of the range, and probably 

 dipping beneath the adjoining basalt. The washing of the granite 

 detritus gives from 3 ozs. to more than 2 lbs. of ore per dish (of 

 about 20 lbs.). The older drift is rather poor in tin to within about 

 a foot of the bottom ; but the bottom layer is in part very rich, some 

 having yielded as much as 6 lbs. of ore per dish. 



The author also described the Grlen Creek, about 40 miles north of 

 the Elsmore mine, from the surface deposits of which tin-ore has 

 been obtained by washing. The course of the creek is mostly 

 through a black hard slate destitute of fossils ; but at one part, for 

 about 10 chains, its bed consists of a fine-grained hard granite, with 

 numerous veins of arsenical and copper pyrites, and one solid vein 

 of tin-ore, about J in. in thickness, all of which pass from the granite 

 into the slate without any interruption or change, the passage from 

 one rock into the other being also gradual. 



_ The chief underlying rock of the district is a black slate, but 

 dispersed through it are small outcrops of a rather coarse-grained 

 micaceous granite, close to one of which several veins of solid tin- 

 ore, from 1 to 4 inches thick, have been found traversing the slate 

 rock. The tin- ore disseminated through the surface-deposits has 

 been derived from these veins and from a very hard and tough 

 greenstone (diabase), which occurs in large dykes and patches in 

 various places, and is probably younger than the granite. 



In conclusion the author referred to the probability that a defi- 

 ciency of water may prove a great obstacle to the full development 

 of the tin-mining industry in this district, but stated that "it seems 

 not unlikely that the production of tin-ore from this part of Australia 

 will reach, if not surpass, that of all the old tin-mining countries 

 combined." 



Discussion. — Mr. Daintree commented on the enormous yalue of the 170 miles 

 of frontage for stream-tin works exposed in Queensland. The value of these alone 

 would, according to Mr. Gregory's calculation, be some £13,000,000; taking an 



