Try the US Mint website, that should be accurate enough for you.
http://www.usmint.gov/about_the_mint...s&type=bullion
http://www.mining.com/7-reasons-the-...0-again-29308/
As for 285 gallons of oil to raise one head of beef, that's so absurd even a primary school kid could work out that there would be no beef in the world because it would be completely uneconomical. Are you sure it wasn't .285 gallons? lol
Back to school for you airedale, I ship my weaners in at about $400 and sell them a year later for about $1,000. I don't fertilise, and feed them the smallest amount of hay or silage, it's nonsense. If it cost me anywhere near that amount I wouldn't even bother.