Here’s another neat info-graphic from the folks at Demon-ocracy, this one depicting a variety of mostly silver (with some gold) bars, balls, and blocks of bars from which the image below was culled.
As detailed here, silver is a very dense metal, but gold is even denser (though not as dense as platinum) which explains why the gold cube above is slightly smaller than the silver cube. Interestingly, while the value of the gold cube above is about $52 million, the silver cube is worth less than $1 million.