(MB) After a slight dip in the dollar index, base metals prices on the London Metal Exchange were up across the board during morning trading on Tuesday July 17, despite US-Sino trade tensions continuing to weigh on market sentiment. The slight downtick in the US currency comes ahead of a congressional testimony on the US economy and monetary policy by Federal Reserve chairman Jerome Powell, due to be delivered this afternoon. Leading the broad uptrend as a result, zinc prices climbed more than 2% during the morning session, after closing at their lowest level in over a year on Monday. “We regard the [zinc] price slide, which was presumably exacerbated by the withdrawal of speculative financial investors, as excessive. It is true that two new zinc mines went into operation in recent months and that production is being ramped-up there, meaning that more supply is available,” Commerzbank Research said in a morning note.