How were minerals in the sea / ocean formed?

Question

I need a simple answer which is easy to understand. Just a brief outline, nothing to complicated. It's part of my S&E assignment - any good links on ocean minerals and mining for minerals in the ocean would be great too! Thanks!! =]

(of course I will give 10 points for the best answer - lol)!

Answer 1

http://www.csiro.au/science/MiningMinera...

Answer 2

probably from the rocks in the ocean...idk worth a try