The base metals were primarily in the red on Wednesday.

Copper faced its bugaboo, the $4 mark, almost making it there in the pre-dawn hours before declining through most of the trading day to finish at $3.9376/lb., down more than 4 cents. Nickel fell back through the $13 mark, yet again, closing at $12.8639/lb., down 17¾ cents. Zinc fell below the 99 cent mark in the early morning, but managed to rally back over a buck, ending at $1.0032/lb., down two-thirds of a cent. Aluminum was a modest gainer, adding more than a third of a cent, to $1.3745/lb., while lead lost just over two cents, to $1.2685/lb.

Copper fell by the most in two weeks, as demand concerns took precedence over supply worries on this particular day.

The metal skidded despite some strength in the equities markets and the positive trading in the dollar, which makes commodities denominated in dollars more expensive for holders of other currencies.

“It’s not just metals. The whole commodity sector is weaker. The dollar is a little bit stronger in comparison with where it was yesterday. People are taking some chips off the table,” said Eugen Weinberg, a commodities analyst at Commerzbank.

The metal was also affected by a report out of Chile quoted a leader of striking workers at Codelco, the world’s largest copper producer, as saying that government-mediated meetings with the state-owned company may resume.

The report said a settlement had been reached with unions representing striking workers at the Teniente mine, and that the Chilean Mine Minister has called for a quick resolution to the problem.

“There is a real incentive to get it done … to try and move the copper out as quickly as possible rather than sitting on it,” said Steve Platt, a futures analyst with Archer Financial Services in Chicago.

“That certainly will affect sentiment. At this juncture, I think the dollar, questionable demand from China, and the prospects of a resolution are probably all combining to make for a weaker tone,” Platt added.

Meanwhile, aluminum bucked the downtrend by remaining firm.

The metal’s strength “is being driven by news from China that power stations’ coal reserves have dropped to only 12 days’ worth of supplies, down from 15 days in March,” Weinberg said. The government’s minimum guideline is 14 days.

Almost 80% of China’s electricity is generated from coal and that a shortage would mean a big hit to production of aluminum, the most energy-intensive metal.