72 
rock is that it is gold-bearing. The hand specimen in my pos- 
session shows a small speck of metallic gold imbedded in it. I 
do not know whether I am correct in so saying, but I believe this 
this to be the first recorded occurrence of gold in a volcanic rock 
for South Australia. Whether it really occurs as an original 
constituent or not it would be impossible to conjecture from the 
evidence at my disposal, but the field-occurrence is at least well 
worth an investigation. Supposing that it is not an original con- 
stituent, it is easy to understand how a lava flow in passing over 
auriferous sands or gravels might catch up and include some of 
the gold, as has been the case with the zircons occurring in the 
basalts of the Eifel District in Europe. On the other hand, 
if the basalt occurs as a dyke-rock,* the dyke may have inter- 
sected an auriferous quartz reef and caught up some particles 
of gold or-auriferous quartz. The quartz, in the presence of 
such basic materials as compose this rock, would be corroded and 
finally dissolved away, leaving the gold as an included speck. It 
is curious that the speck should occur in such a small hand speci- 
men as J have, the dimensions of which are not greater than 
about 24” x 14” x 2” 
The rock is fine-grained and compact. Another point of some 
interest is that, although it is a basalt, still the magnetite in it 
is not large in amount, and most of the minerals composing it are 
colorless, or nearly so. On one edge of the specimen and in one 
or two other places there are some reddish-brown clear minerals 
of high refractive index, which appear to be either garnet or zircon. 
As they do not appear in section it is very difficult to say which. 
The specimens of this mineral are not large, but are quite easily 
seen by the unaided eye. 
IV. AxinitE AMPHIBOLITE, Rosetta Head, S.A. 
This is a very much altered rock, which consists mainly of 
hornblende and a perfectly colorless awgite, the former largely pre- 
dominating. Some biotite is present in minute crystals, with 
quartz and chlorite as accessories. It has been much altered, as 
evidenced by the chlorite, &c. The one great point of interest in 
this rock is the presence of a considerable amount of the mineral 
axinite as a rock-forming constituent, which occurs not only as 
allotriomorphic grains but also as idiomorphic crystals, which in 
section give most perfect lozenge or hatchet-shaped sections. In 
one part of the hand specimen there is a small druse or cavity, 
* This rock was observed at Kingscote by Prof. Tate in 1881 and in the 
Freestone Range in 1883 ; it was reported a diorite intrusive in mica-schist 
in Trans. Roy. Soc., S.A., vol. vi., p. 122, 1883, and in the accompanying 
geological map its course is laid down, though by inadvertence was not 
prolonged to the sea-cliff at Kingscote.—[EDITOR. ] 
