The Varying Value of Platinum Metals

It is a common apprehension that platinum is much more expensive than gold. The prices of noble metals varies, depending on supply and demand. In the middle of the 1990s, platinum and gold prices were on the same level but the increased industrial use for catalytic purposes has increased the PGM prices considerably. Table 32.7 illustrates this with examples from three occasions. 

The concentrations of platinum group elements are extremely low in natural environment Nor do the elements any role in Hfe. The drug dsplatin is of course, Hke all potent drugs, very toxic. The oxides RuO, and OsO, are also toxic. 

The mean contents in the earth s crust of all the platinum group elements are as mentioned very low. In the light of this fact it is astonishing that very high concentrations of iridium have been found in sedimentary rocks from the time of transition from the cretaceous to the tertiary geological period. At this time, about 70 million years ago, extinction of many biological species, including the dinosaurs, occurred. 

The iridium in these rocks is supposed to have arrived with a giant meteorite, the impact of which raised debris in such quantity that solar radiation was absorbed for a long time, changing the earth s climate [32.9]. 

McDonald and L. B. Hunt, A History of Platinum and its Allied Metals, Johnson Matthey, London, (Europe Publications Ltd), 1982 

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