There is more gold in mobile phones than there is in gold ore.
Mobile phones contain a surprising amount of gold – it is used on the motherboard. It turns out that gold mining is very inefficient – you need to mine about a tonne of gold ore to get 1g of gold (Minecraft, you lie to me). But you need between 35 and 41 phones to get an equivalent amount. That means that mining motherboards for gold is almost 300 times as profitable as actual gold mining.