If you think that the most expensive metals - a gold and platinum, you're wrong ...) $)
The most expensive metal is California. The price of one gram of California ranges from 6, 5 to 10 million dollars !!! .. in fact the world, there are not more than 10 grams of metal.
California is not there in the environment and is produced only by laboratory tests.
To date, the reactors can produce California, the world's only two - the United States and Russia. Together they are able to produce for the year only 80 micrograms of California.
Californium bomb the most powerful in the world (1 gram of californium-252 - is about 3 trillion neutrons per second - the small hours of operation of a nuclear reactor).
Californias used for emergency treatment of cancer in the last stages.