A sluggish summer for the price of gold could be over. It's back at levels last seen in May.

December gold increased $19.90 Tuesday to end at $1,642.90 per ounce. It is up about $35 since Aug. 1.

Traders hope authorities in the U.S., Europe and China will take additional steps to promote economic growth in their countries. Gold can benefit from such measures because it is used as a hedge against inflation.

Optimism is growing after Spain raised $5.4 billion from bond investors at sharply lower interest rates. Traders are also awaiting Wednesday's release of minutes from the recent Federal Reserve meeting to search for hints about possible Fed action.

In other trading, prices are higher for metals, oil, grains and beans. Natural gas is lower.