452 Norman Taylor — The Cudgegong Diamond Field. 



In the drift also may occasionally, though rarely, be found some 

 Carboniferous conglomerate pebbles. Bounded pebbles of coral 

 (Favosites Gothlandica) are not uncommon; shales with Glossopteris, 

 and various Upper Silurian, or Devonian fossils (Orthis, Spirifer, 

 and Crinoidal stems), as before mentioned, together with silicified 

 wood, have been observed in this drift in the so-called " floating 

 reef." The neivest drifts (upper and lower), comprising the present 

 river-bed, and the older and deeper channels, contain pebbles, 

 boulders, and shingle of the neighbouring sandstones, slates, cal- 

 careous grits, red flinty porphyries, felstone, Carboniferous con- 

 glomerates, quartz of all kinds, greenstone, and silicified wood. A 

 very noticeable feature in these drifts is the prevalence of blackish 

 quartz pebbles and grains, inclosing crystalline felspar, which are 

 evidently derived from the granite of Aaron's Pass, on the Mudgee 

 Eoad, south of the village of Cudgegong. The basalt, which might 

 have been expected to be present, must, from its easy decomposition, 

 have been entirely washed away, and is nowhere seen except in the 

 immediate neighbourhood of basalt escarpments.- Garnets, in minute 

 brown rhombic dodecahedrons, with angular replacements, occur, 

 and also cube's of oxide of iron (pseudomorphs after iron pyrites), 

 locally termed " Devil's dice." Many diamonds were obtained from 

 the river-bed ; but in every case, only where the older drift has 

 been discharged into the river by the miners during gold- washing 

 operations. 



The following are descriptions of the gems and other minerals, 

 found in the diamond drifts, with the analyses of some of them by 

 the late Professor Thomson. 



Diamond. — The diamond itself is distributed through the older 

 drift very sparingly and irregularly, and does, not appear to be 

 confined to any particular level in the drift deposit, though the 

 lower five or six feet are generally taken out by the miners, in 

 consequence of the certainty of finding gold in that portion. The 

 fact of the very frequent occurrence of diamonds on the waste heaps 

 round the mouths of the old shafts sunk for gold, is enough to 

 suggest that the diamond may occur in the higher portions of the 

 deposit, since the bottom layers only have been carted to the river 

 for gold- washing. One diamond, in situ, occurred three feet from 

 the bottom, imbedded in a mass of loosely cemented quartz pebbles 

 the size of peas. As regards the weight of the diamonds, the follow- 

 ing parcels afford a fair average : — 



106 diamonds weighed 74| carats, the largest If carats. 



°1 >) D 1" )> )> la j> 



HO „ „ 26§ „ 



16 „ „ 6 „ 



700 „ „ 151| „ 



giving an average of - 23 carats each, or nearly one carat grain. 

 The largest gem discovered was a colourless perfect octahedron, 

 weighing 5f carats ; it was found in the river, between the " Two- 

 mile-flat" and the "Kocky ridge," at a spot where the older drift 

 had been discharged in gold- washing. Another large stone, weigh- 

 ing 3^ carats, was found, by a boy, lying on the sandy bed of a dry 



