Platinum
This metal is steel-gray in color, very malleable and ductile, almost infusible and resists the action of acids. It is one of the “noble” metals, much rarer than gold, and so has become popular for jewelry. It is also used in the manufacture of sulphuric-acid, in nitrogen-fixation plants, for chemical utensils, in the electrical industries, and in dentistry. Platinum in its occurrence is associated with the certain other equally rare elements, like iridium, palladium and osmium. Its use has increased rapidly of late, but the supply has not kept up with the demand, so that, whereas in 1906 platinum and gold were about equally valuable, now the platinum brings about five times as much as the gold.
[Platinum]
Pt
Occurs in grains or nuggets; hardness 4.5; specific gravity 19 (21 if pure); color steel-gray; luster metallic; opaque.
This rare metal is mostly found in placer-deposits, often with gold. It comes originally from dark igneous rocks, like peridotite, pyroxenite, etc., and platinum is found to be associated with the nickel ores of Sudbury, Canada. While formerly 90% of the world’s supply of platinum came from placer mines in the Ural Mountains, today more than half is produced in Canada and about a fifth in Russia. In the United States it is found in California, Oregon, Nevada, and Alaska.