RARE METALS AND THEIR DISTRIBUTION. 10J 
Na z 0 
— 
— 
.04 
Si() 2 
16.19 
U5-30 
12.72 
IMP 
. 
— 
1.08 
Ta 2 0 5 
.67 
.40 
•47 
H 2 0 + 
12.04 
8-37 
4.16 
HO- 
.88 
4.19 
3-50 
Radium and Helium 
present 
present 
present 
100.05 
100.05 
99-5^ 
S P- g r - • 
4-45 
4-13 
4.68 
Platinum and the Platinoid Metals— The noble metals 
of the platinum group form two sub-groups, viz.: 
(a) Platinum, iridium and osmium ; 
( b ) Ruthenium, rhodium and palladium. 
They are invariably found associated with one another 
near the outcrops of rocks of a basic or ultrabasic type. In 
this and in many other respects they differ from all other 
rare metals, particularly in occurring in nature almost 
invariably in the metallic state uncombined with non- 
metallic elements. The exceptions are Sperrylite (platinum 
arsenide) and Laurite (ruthenium sulphide). All the metals 
of this group are “ noble ” metals, i.e., particularly resistant 
to the action of the air and most common chemical agents. 
Platinum was first described in 1755, the other metals in the 
group have been known since early in the 19th century. 
Lately a claim has been put forward for the recognition of a 
seventh metal of the group which has been named Canadium. 
Its existence, however, requires confirmation. 
Platinum is by far the most abundant of these metals 
and is indispensible to many industries and arts. Its de- 
mand for jewellery and for acid and fire-resistant chemical 
ware, and for electrical purposes, is very large, f million 
pounds’ worth being used in the United States alone during 
1910. 
Iridium is the next most important of these metals, 
being largely alloyed with platinum to harden and strengthen 
it. 
Osmium, palladium and rhodium are utilised to a small 
extent. Ruthenium, the least abundant of these metals, 
has no practical application. 
None of these metals has yet been proved to occur in 
this State, though ultrabasic rocks, the jons el origo of such 
metals, are fairly common and widespread, as, for example, 
at Kalgoorlie, North am and Soanesville. A good platinum 
deposit would be worth infinitely more at the present time 
than a correspondingly rich gold deposit. 
