Commodities aren't "investments" in the traditional sense. You don't buy them expecting to make money on them - or if you do, you're missing the point.
With a interest bearing savings account, bonds, etc, you count on the set interest payments to increase your account value.
For stocks, you count on dividends, or that the fundamentals of the company indicate that the value of the company will increase.
For commodities, there's nothing like this. Buying them expecting value to increase is essentially gambling. Yes, if you hear that some big gold mine somewhere shuts down, you can expect gold prices to go up (as an example)- but in terms of raw investment status, commodities aren't expected to do the same thing as "normal" investments.
The point of commodities is to retain a fixed buying power. In times of inflation, the money you have held in commodities doesn't devalue, like it does in other places.
The point is, don't make the mistake of plowing a bunch of money into gold/silver/etc expecting to make huge profits, or to retire on it.