Gold and silver prices are posting good advances in early U.S. trading Monday, boosted by another sharp decline in the U.S. dollar index, which hit a two-week low overnight. A dip in U.S. Treasury yields to start the trading week is also a positive for the precious metals markets. More short covering in the futures markets is featured. October gold was last up $14.50 at $1,732.80 and December silver was up $0.683 at $19.445.