6 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [NoY. 6, 



dominant rocks are granite and basalt, enclosing subordinate 

 areas composed of metamorpbic slate and sandstone, whicb latter 

 show in places intrusions of greenstone of very limited extent. The 

 basalt bas mostly broken tbrougb tbe highest crests and points of 

 the ranges and spread in extensive streams, the surface of which is now 

 more or less decomposed, over the country at the foot. Thus we see fine 

 valleys, with fertile basaltic soils several feet in depth, bounded by 

 well-wooded granite ranges, not perhaps exceeding 300 ft. in height, 

 a beautiful park-like country, well watered by extensive creeks and 

 small rivers, and with a climate similar to that of Central Europe ; 

 for the summer temperature rarely exceeds 80° F. in the sbade, 

 whilst during the winter months, June and July, there is frequently 

 snow and ice. 



Perhaps the richest mining-area as yet discovered is that of the 

 Elsmore Company, situated about 12 miles east of the township of 

 Inverell. It lies on the north-western side of the Macintyre river, 

 and includes a granite range about 250 ft. in height and nearly 

 2 miles in length, dipping on all sides save tbat towards the river, 

 beyond which the rock extends a considerable distance beneath ba- 

 salt. The granite is micaceous and rendered porphyritic by crystals 

 of white orthoclase, which frequently reach several inches in size ; 

 bluish grey oligoclase is also, though sparingly, associated. It is 

 traversed by quartz veins several inches to above a foot in thick- 

 ness, which contain cassiterite in fine druses, seams, and solitary 

 crystals. Portions of these veins are highly micaceous, and represent 

 in fact the rock called "Greisen" characteristic of the tin-ore-dis- 

 tricts of Saxony and Bohemia *. Of far greater importance, however, 

 than these veins are dykes of a softer kind of granite, which consists 

 perhaps for 75 per cent, of its mass of small scaly greenish mica, and 

 the remainder of felspar, quartz being but very rarely observable. 

 Through these micaceous dykes cassiterite is not only well distributed 

 in implanted crystals from the size of a pin's head to above that of a 

 pea, but it occurs also in irregular veins of several inches thick- 

 ness, and in nests and branches yielding lumps of nearly pure ore 

 up to above 50 lbs. in weight. Part of the mass of one of these 

 dykes forms a regular breccia of mica and imperfectly crystallized 

 tin-ore cemented by hydrous oxide of iron. 



The actual number of such dykes traversing the granite range is 

 not known as yet : I saw six of them, each several feet in thickness ; 

 but there can be no doubt that more will be found when the ground 

 is more minutely prospected than has hitherto been the case. It 

 would astonish any European tin-miner walking over the range, to 

 find along the outcrops of these dykes large blocks of the micaceous 

 granite studded with moss- and lichen-covered druses of large crystals 

 of cassiterite, or frequently to pick up weathered pieces of pure 

 tin-ore several pounds in weight. After seeing the place and being 

 informed that throughout the large area belonging to other Mining 



* In the tin-ore localities of the Beeckworth gold-field, Victoria, this rock 

 occurs also in a similar manner ; but the surrounding granite is there very fine- 

 grained aud highly felspathic (euritic) and rarely shows porphyritic texture. 



