220 
Maitland. — Westeryi Australian Geology, 
■with plane surfaces have yet been mot witli. It has pointed out 
by one of the leading living mineralogists of Ureat Britain that 
‘•with the occurrence of such large crystalline masses of telluride 
there can be but little doubt that one day crystals Avill be found, 
and these will in all probability surpass those hitherto met with 
from other parts of the world.” 
The ultimate derivation of the gold in the Boulder group or. 
lodes would appear to have resulted from the action of a later 
series of igneous intrusions than that in which the ore bodies are 
contained. It may be that the introduction of the gold bears an 
intimate relationship to the after-effects of the intrusive granite 
which makes such a prominent featurt' in the country adjacent to 
Kalgoorlie on the north, but which has not reached the surface 
in the vicinity of Boulder, though it is probably reju'esented by 
the acid dykes which traverse the held. 
One remarkable and outstanding featui'e in the State is its 
iron ore resources, some of which are probably e<pial in size vj 
other known deposits in tlie Avorld. ^hle most important class of 
ores in Western Australia are the large de])Osits of haematite 
associated with hne-grained sedimentary (puirtzites; these pass by 
all gradations through varieties of jaspilite to pure iron ore. 
The ores themselves, in the light of such knowledge as is at 
present available, appear to owe their origin by hydrothermal pro- 
cesses, which collected and re-deposited the iron from adjacejjt 
basic igneous rocks. The highly ferruginous bands are generally 
found to follow the bedding and other structural planes of their 
hosts very closely, indicating tliat the solutions responsible for 
tlie deposition of the iron ore were to a very large extent con- 
trolled by the stratification. In some cases, however, there is 
distinct evidence of a complete replacement of the siliceous rocks 
by haematite, indicating tliat it has in j)art, at any rate, replaced 
the beds which have shared in the severe folding, faulting and 
compression to which they have been almost everyAvhere subjected. 
The ultimate source of these enormous cpiantities of iron ore 
is as yet one of the many unsolved geological problems upon which 
much intensive research, both in the field and in the laboralory, 
is required. 
An interesting occurrence of a chrome iron ore of some scien- 
tific importance has recently been discovered by Mr. Blatcliford 
from the neighbourhood of ilurrunda, a range of hills forming 
the headwaters of Skeleton Creek in the Xorth-West Division. The 
deposit lies in a belt of serpentine about 80 chains in Avidth, ami 
the ore occurs in a series of mass^ive lens-shaped or pod-like liodies 
