An ostler (hostler) looked after horses. There used to be horses in mines.
Because Nathan is so awesome the world just explodes.
Theirs not to reason why Theirs but to do and die. Part of Alfred Lord Tennyson's, The Charge Of The Light Brigade
Generally speaking, minerals. Obviously, it depends on the type of mine, but you can mine for coal, gold, diamonds and even uranium, among many others.
Bronze is an alloy of (usually) copper and tin. We mine the metal ores separately and then combine them to make bronze.