144 A. LIVERSIDGE. 



The nugget photographed on Plate X, came from the 

 Rockhampton District, Queensland, and although it is more 

 or less completely bounded by faces, these appear to be 

 merely the bounding surfaces of the cavity in which the 

 gold was deposited between quartz crystals lining a small 

 vug or hollow. It weighed 35*7 gm. and the quartz crystals 

 removed by hydrofluoric acid weighed 1*63 gm. 



The nugget enclosed well developed hexagonal crystals 

 of quartz ; these were dissolved out by hydrofluoric acid, 

 and the cavities showed that the prisms were capped by 

 equally well formed pyramids; as it was not possible to 

 obtain good photographs of tlie pseudomorphous cavities, 

 a mould was taken in flexible glue; this mould was coloured 

 with white paint and photographed, with the results shown 

 in figure 2, Plate X. The pyramidal terminations, however, 

 are imperfect from the mould having broken slightly in 

 removal. This is the only example I have come across of 

 well formed quartz crystals enclosed in gold; whereas 

 pieces of irregular quartz vein stuff are very common in 

 gold nuggets. 



Figure 1 shows a cut and polished section of the gold; 

 the principal cavities left in it after removing the quartz 

 crystals by hydrofluoric acid, are indicated by arrows as 

 they do not come out very well in the photograph. The 

 chief point, however, is that the gold does not show the 

 presence of concentric layers round the quartz crystals, as 

 might have been expected, nor does it show a well marked 

 crystallized structure; it, however, presents a silky sheen, 

 due probably to the same cause as the sheen in Satin Spar 

 and other similar minerals. 



Two gold crystals, well formed rhombic dodecahedra, 

 from New South Wales, are shown enlarged in Plate XI, 

 figures 1 and 2. Figures 3 and 4 show the same crystals, 

 but the faces in each have been filed down, polished and 

 etched. 



