224 SYSTEMATIC DESCRIPTION OF rRECIOUS STONES 



times rough and dull. No spheres of bort, such as are found in Brazil and South Africa, 

 appear to occur in Australia. 



Solitary specimens of diamond have been found at many other places in this district. 

 At Bald Hill, near Hill End, on the Turon river, a stone of 5^ carats was found, and a 

 number of diamonds, which though of small size were of excellent quality, were met with in 

 the old gold-mines of Mittagong. Again, near Bathurst, a black diamond, the size of a 

 pea, and having the form of an almost spherical hexakis-octahedron, was found. Diamonds 

 have also been collected from the gravels underlying the basalt at Monkey Hill and Sally's 

 Flat, in Co. Wellington, just as they occur at Mudgee. Uralla, Oberon, and Turnkey are 

 other localities at which more than solitary specimens of diamonds have been found. 



The occurrences mentioned above were all in ancient river gravels; among existing 

 water-courses in which diamonds have been found may be mentioned the Abercrombie, 

 Cudgegong, Macquarie, Brook's Creek, Shoalhaven, and Lachlan rivers. The stones found 

 in existing streams are much worn, and many are broken ; from this, and also from the fact 

 that the minerals forming the gravels of these water-courses are identical with those of the 

 ancient i-iver deposits found underlying the basalt, we may conclude that the gravel of the 

 present rivers is redeposited material derived from the ancient river-beds. 



The mode of occurrence of the diamond in the north of New South Wales, especially in 

 the district of the Gwydir river, in the neighbourhood of Bingera and Inverell, is of some 

 importance. As pointed out by Professor A. Liversidge, diamonds are found in the valley 

 of the Horton or Big river, seven or eight miles from Bingera, under just the same conditions 

 as at Mudgee. The diamond-bearing deposit is 2 to 3 feet thick, and occurs in isolated 

 patches, the material which originally lay between having been denuded away. These 

 patches of diamantiferous material are scattered over an area measuring four by three miles, 

 in a valley which is opened towards the north, but enclosed otherwise by the Drummond 

 Range. The deposit consists of sandy and clayey material, and has probably been deposited 

 in former times by the Horton river. The-rocks of the locality are clay-slates of Devonian 

 or Carboniferous age, and the sheet of basalt which occurs in the neighbourhood appears 

 to overlie deposits similar to those now being considered. Here also the diamantiferous 

 material is in places cemented together to form a solid conglomerate ; it includes boulders 

 and fragments of the underlying clay-slates, and, when clayey, contains crystals of gypsum. 

 The associated minerals are practically the same as at Mudgee, barklyite is, however, here 

 absent. Black tourmaline is regarded as a specially characteristic associate of the diamond, 

 and its appearance is hailed with joy by the miners. 



Diamonds occur here rather more plentifully ; they are colourless or straw-yellow 

 and small, the largest weighing only 2f carats. On an average only twenty stones 

 are found in each ton of material, and a stock of 1680 stones weighed no more than about 

 140 carats. 



More recently diamonds have been discovered in the tin-gravels of the neighbourhood 

 of Inverell, and their occurrence here appears to be sufficiently abundant to justify systematic 

 working. Cassiterite (tin-stone), rock-crystal, sapphire, topaz, tourmaline, monazite, &c., 

 are here associated with diamond ; gold, however, is apparently absent. Several companies 

 have been formed, and many thousands of stones, averaging ;^ to J carat in weight, have 

 been obtained from the different mines; the largest of these stones weighed 3f carats. 

 From the Borah tin- washings, situated at the junction of Cope's Creek with the Gwydir 

 river, 200 stones were obtained in a few months, the largest of which weighed almost 1^ 

 cai-ats ; while in the Bengonover tin- washings, only a few miles away, a stone weighing nearly 

 2 carats was found. Diamonds have also been found in most of the alluvial tin- workings 



