Money laundering is the process of making illegally-gained proceeds (i.e. dirty money) appear legal (i.e. clean). Typically, it involves three steps: placement, layering, and integration. First, the illegitimate funds are furtively introduced into the legitimate financial system.
Here is information about a currency bill, According to the Bureau of Engraving: * Our present sized currency measures 2.61 inches wide by 6.14 inches long, and the thickness is .0043 inches. * The approximate weight of a currency note, regardless of denomination is (1) one gram. $1,000,000 is 10,000 $100 bills, which weighs 10 kg or about 22 pounds. If stacked in one stack, the height would be 43 inches high or about three and one half feet. Easy to carry in a briefcase if that is what you had in mind.
The typical gold bar held in the bank's vault weighs 400 troy ounces (roughly 27 pounds), which at the current price per ounce means each bar is worth $680,000. The gold bars are stacked neatly on six shelves per stack. Each shelf holds around 82 bars which means each level of a single shelf is worth $56 million and the whole stack is worth $336 million. In this photo below, you can see at least 11 stacks worth roughly $3.7 billion: