SAN FRANCISCO (MarketWatch) -- Gold futures settled with a loss on Tuesday, their third in a row, on the back of strength in the U.S. dollar DXY, +0.03% . June gold gcm5 fell $2.10, or 0.2%, to settle at $1,183.20 an ounce on Comex. Prices also marked a second straight monthly loss, losing roughly 2.5% for the month.