CRYSTALLINE STRUCTURE OF GOLD NUGGETS. 75 
ginous matter; the lighter coloured parts are the gold. Weight 
‘7 oz. Troy ; assay *8795 gold and 1150 silver. Externally this 
nugget showed a foliated structure and the presence of ferruginous 
matter. 
The first figure on Plate 7, is the section of a gold nugget from 
Wellington, New South Wales, weight -99 oz. Troy, Mint assay 
of parcel, gold -9335, silver -0600. Externally this nugget seemed 
to be massive gold, but the section showed the presence of much 
ferruginous matter; the bending and welding over of the gold 
thus enclosing the impurity is well shown by the photograph. 
The three following New South Wales specimens also show 
much enclosed ferruginous matter, and a minutely crystalline 
structure, 
The next specimen on Plate 7 represents a section of particularly 
bright gold from Peak Hill, this weighed -92 oz. Troy, Mint assay 
= gold -9790, silver 0100. No visible impurity was present, the 
black and dark parts are crystals of gold; from the large size of 
the crystals this nugget looks as if it had belonged to a much 
larger piece, but not necessarily so. The crystal sections have 
a satiny sheen, not visible in the illustration, as if made up 
of thin plates. The interpenetration of the crystals is well shown. 
This nugget is purer than usual and such gold generally yields 
larger crystals, this is the case also with ingot gold. 
The nugget from Parkes, New South Wales, Plate 8, shows a 
different structure to any of the preceding ; it is minutely crystal- 
lised and contains rounded enclosures of iron oxide. Weight 5°4 
02, Assay = -9265 gold. 
Sections of many other nuggets were made and photographed, 
but as they did not differ materially from those described herein 
they are not figured, A nugget from Hill End, New South Wales, 
showed under a one inch objective a small cavity lined with quartz 
crystals. In others the cavities were lined with minute crystals 
of gold. 
Piatinum NuacGer. 
The section of a nugget of platinum weighing thirty-six 
§rammes, sp. gr. 15-87 was also prepared, polished and etched by 
