, chromium from 2 to 7 per cent., vanadium from 1/2 to 1-1/2 per
cent., carbon from 6 to 8 per cent., with perhaps cobalt up to 4 per
cent. Molybdenum or uranium may replace part of the tungsten.
Some of the newer alloys for high-speed tools contain no iron at all.
That which bears the poetic name of star-stone, stellite, is composed of
chromium, cobalt and tungsten in varying proportions. Stellite keeps a
hard cutting edge and gets tougher as it gets hotter. It is very hard
and as good for jewelry as platinum except that it is not so expensive.
Cooperite, its rival, is an alloy of nickel and zirconium, stronger,
lighter and cheaper than stellite.
Before the war nearly half of the world's supply of tungsten ore
(wolframite) came from Burma. But although Burma had belonged to the
British for a hundred years they had not developed its mineral resources
and the tungsten trade was monopolized by the Germans. All the ore was
shipped to Germany and the British Admiralty was content to buy from the
Germans what tungsten was needed for armor plate and heavy guns.
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