Commodities books: Classic in the field?

[RandBriscoe]

Just got my first gig out of school, in the back-office side of the commodities industry (precious metals mainly). As an econ grad, I didn't get heavy into the technical aspects of futures, options, hedging etc. As a result, I'm trying to learn more about this part of the business.

Are there any books considered sort of the HEPFAP of commodities? Generally considered a classic? I'm trying to avoid the crap that tries to get you to trade with the author's firm.

Thanks for any help...