Precious Metals is a quest in Orzammar. You get the quest in Dust Town from a dwarf named Rogek. If you talk to Rogek one of the options you have is to buy some unrefined Lyrium ore from him for 50G. If you have persuade you can get the ore for 40G. The ore is to be sold to Godwin, a low level mage in the Circle of Magi. You can find Godwin in the Senior mage quarters. If you have cleared the Circle Tower quest you will have already met Godwin, he's the mage that you found hiding in the clothing cabinet.
When you speak to Godwin you can extort him for 8G. He also offers to buy the Lyrium ore for only 50G, but if you have coercion you can opt to ask for 75G or 60G. With a coercion level 2 you may only 53G. With coercion level 3 Godwin will agree to give you 60G - the total earnings with the intimidation for 8G would have been 28G.