WE get some metals from the sea but most from the Earths crust. The crust is the outer layer of the earth its a huge mixture of many different compounds it also contains elements such as sulfur, silver platinum gold these occur uncombined or native because they are nonreactive. if you could dig up the earths crust you would find that its almost half oxygen its composition
oxygen 45% (nearly 1/2) silicon 27% (more than 1/4), aluminum 8% (the most found metal in earth crust), iron 6%, calcium 5% magnesium 3% sodium 2.5% potassium 1.5% all the other metals and non metals 2%

nearly three quarters of the earth is non metal: these non metals are oxygen and silicon