ORES OF GOLD 49 
far eastward at the level of between 1400 and 1200 feet, 
descends to the lowlands of Central Australia. The plateau 
Consists of pre-Paleozoic gneiss and schists invaded by 
Sranites gpg acid dykes, and by basic intrusions some of 
Which are now amphibolite and horablende-schist. Some 
of the micq schists, chlorite schists, and slates were sedimen- 
“ary rocks. 
Gold wag discovered in Kimberley in North-western 
Australi, in 1882 and at Yilgarn, 200 miles E. of Perth, in 
188;. Active mining followed the discovery of the gold 
at Coolgardie in 1892, but was delayed by the scarcity of 
nr 
D 
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_— 
50’ 
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Fra, I4.—THE ASSOCIATED NoRrTHERN Ore-Bopy, KALGOORLIE, 
The Associated Northern ore-body, at Kalgoorlie (after a: The 
Primary fault F1 Separates the dacite (D) from altered tuffs (¢). The 
ore-body wag formed in the tuffs in connection with two subsequent 
fang (F,, F,). 
Water. That field proved disappointing as the gold is in 
shallow, though rich patches. The mining fortune of Western 
Australi, has been dependent mainly on the Golden Mile at 
Boulder, Kalgoorlie, which was discovered in 1895, and has 
deen claimed as the richest square mile known in mining 
Ristory, The treatment of the complex ores of Kalgoorlie, 
Neludipg sulphides, sulpharsenates, sulphantimonates, copper 
Sulphide, and tellurides, was of exceptional difficulty, and 
Vas Managed by the introduction to mining of many new 
Processes, including the pebble-mji] and filter-press. The 
lodes of quartz intergrown with black rock were regarded 
°Y E. F. Pittman (1 898) as intrusive dykes ; but H. P. Wood. 
Yard (189g) explained them as due to the ascent through 
Ssures of gold-bearing solutions which impregnated the 
ck on both sides, This view was confirmed (1898) by