Norman Taylor — The Cudgegong Diamond Field. 453 



creek, running down the centre of the " Two-mile-flat." During the 

 first five months of systematic washing, over 2,500 diamonds were 

 discovered, and several thousands more were afterwards obtained ; 

 but, as the collectors were generally rather reticent as to their finds, 

 the exact numbers could not be ascertained. The gems were mostly 

 pellucid and colourless; many have a straw-yellow tint, and tints 

 of brown, light or dark bottle-green and black are more rarely met 

 with. One or two opaque black ones have been found, and another 

 of a dark green colour, with the external appearance of having been 

 polished with black lead. Black specks within the crystals were 

 not uncommon. The specific gravity, deduced from a number of 

 crystals, is 3*44. They all show a well-defined crystalline form, 

 though irregularities of development are frequent. It is very rare 

 to meet with fractured stones, and these only on cleavage planes ; 

 water- worn stones I never saw from any direct treatment of the 

 undisturbed older drift. Some shapeless diamonds occur, but, if 

 water-worn, the process has not impaired their lustre. They are 

 never found coated superficially with any foreign matter. When dull 

 or lustreless, an examination proved it to be caused, not by any 

 water-wearing or incrustation, but by multitudes of minute angles 

 and edges of structural planes, which gave a frosted appearance to 

 the crystal. The forms met with were the octahedron, twin-octa- 

 hedron, dodecahedron, tris-octahedron, and hexakis- octahedron ; the 

 two latter are often hemihedral, with curved faces, and are some- 

 times developed into flat triangular twins. One specimen of the 

 deltoid dodecahedron or hemihedral triakis-octahedron was found. 



The above-named curious triangular twin crystals are, according 

 to the late Professor Thomson, derivable from the tris-octahedron. 

 If we regard the latter as an octahedron with a low triangular 

 pyramid on each of its faces, and out of the eight pyramids we 

 imagine that only two, corresponding to opposite and parallel octa- 

 hedral faces, are developed, on applying these two pyramids 

 together, they would not form a closed figure, but, by twisting one 

 180° round, we form the triangular twin crystal ; or, more simply, 

 if we inspect a twin-octahedron, there are but two of the original 

 triangular faces entire ; these are opposite and parallel, and, by 

 replacing these two faces by the corresponding planes of the tris- 

 octahedron, the rest of the faces of the twin-octahedron may be 

 obliterated, and the triangular crystal will result. The structural 

 laminae are very distinct in some crystals, and many of the octa- 

 hedrons show these successive layers of growth in a very marked 

 and beautiful manner. A few show indented angles, and sunk 

 triangular depressions on their faces, having the apices of the 

 triangles pointing to the centres of the sides of the triangles in the 

 main crystal. 



Gold. — Occurs fine, scaly, and occasionally inclosed in quartz, 

 The quantity is variable, the average being about three pennyweights . 

 to the load of " wash dirt." 



Osmiridinm. — In minute silvery scales after amalgamation and 

 retorting — only from the newer drift. 



