21% heavier than a pound of gold.

A pound of feathers weighs more than a pound of gold. Let me explain why. Feathers are weighed in avoirdupois ounces, the kind that most of us are familiar with. The common ounce weighs 28.35 grams and 16 ounces makes an avoirdupois pound. A calculator tells us that this comes out to 453.6 grams.

However, gold and other precious metals (and anything that is shot into the air, such as bullets and arrowheads) are weighed in the troy system. Troy ounces contain 31.1 grams and 12 troy ounces make a troy pound. Bringing out the calculator again we see that a troy pound weighs 373.2 grams.