The bubble in precious metals might have popped this week, with silver's violent decline on Friday leading the group lower. Having touched a new record of $120 per ounce earlier in the session, silver has pulled back to$75 in U.S. afternoon hours, now lower by 35% for the day. Gold — which as recently as Sunday had never seen $5,000 per ounce — climbed to$5,600 at one point Thursday, but has now retreated to $4,718, down 12% for the day. Platinum is lower by 24% and palladium by 20%. To put silver's ...