ON THE BlffGEEA AND MTJDGEE DIAMOND-FIELDS. 489 



36. Notes on the Binoeea Diamond -field, with Notes on the Mudgee 

 Diamond-eield. By Aechibald Liveesidge, Esq., F.G.S., Reader 

 in Geology and Mineralogy, University of Sydney. (Read June 

 24, 1874.) 



[Abridged *.] 



The first announcement of the occurrence of the diamond in Aus- 

 tralia was made by the Eev. W. B. Clarke, F.G.S., in 1860. Speci- 

 cimens were found, in 1852, at Calula Creek, and, in 1859, near 

 Sutton's Bar, in the Macquarie river, at Burrendong, and at Pyra- 

 mul Creek. 



In 1867 diamonds were discovered by gold-diggers in the Mudgee 

 district on the Cudgegong river, which flows into the Macquarie. 

 In 1869 they were worked pretty extensively at this spot; and in 

 1870 Mr. Norman Taylor and Dr. Thomson described the Mudgee 

 diamond-field in a paper read before the Royal Society of New South 

 Wales. From this it appears that the diamond-bearing spots lie 

 along the river in outliers of an old river- drift, at varying distances 

 from the river and at an elevation of 40 feet or more above it. The 

 outliers are capped by deposits of hard and compact, sometimes 

 columnar basalt, regarded by Mr. Taylor as of older Pliocene age. 

 These outliers, with their basaltic capping, may be traced for about 

 seventeen miles up the river ; in some of them the diamantiferous 

 drift is still 70 feet in thickness. 



The outliers which have been worked are enumerated by Messrs. 

 Taylor and Thomson as follows : — Jordan's Hill, 40 acres ; Two Mile 

 Flat, 70 acres ; Rocky Ridge, 40 acres ; Horse-shoe Bend, 20 acres ; 

 and Hassall's Hill, 340 acres : in all, 510 acres. The drift has in- 

 variably been met, with in these localities on tunnelling under or 

 sinking through the basalt. In one patch a peculiar deposit of 

 crystalline cinnabar was met with. 



No diamonds have been found in the river-bed, except where the 

 diggers have discharged their tailings into the river, or where gold 

 has been washed. 



The basalt, when not resting upon the drift, frequently lies upon 

 metamorphic shales, slates, sandstones, or greenstone. The general 

 formation of the country is regarded as Upper Silurian, with over- 

 lying outliers of Carboniferous rocks. The rocks in the vicinity are 

 nearly vertical, with a general N.N.W. strike, and consist of red 

 and yellow coarse- and fine-grained indurated sandstones, thin white 

 argillaceous shales, pink and brown fine-grained sandstones with 

 purple stripes, slates and hard metamorphic schists, hard brecciated 

 conglomerate with limestone nodules, flint and red felspar in a 



* [As this paper is to a great extent identical with one communicated by the 

 author to the Royal Society of New South Wales in October 1873, and pub- 

 lished in their * Proceedings,' it is here given only in abstract. — Ed. Q. J. G. S.] 



