There’s lots of gold in urban waste dumps

Gold mining can be a tough and dirty business. Even with relatively rich deposits, usually found in remote areas, you need giant excavators, huge crushing machines, lots of water and highly toxic chemicals, like acids and cyanide, to extract just ten grams of gold (there are 31 grams in a troy ounce) from a single tonne of ore. At current rates, that is worth over $800.