LONDON, Feb 2 (Reuters) – Lead prices eased on profit-taking and a firmer dollar, having hit 6-1/2 year highs earlier in the session on Friday after Chinese mines shut for the winter. Benchmark lead on the London Metal Exchange hit $2,685 per tonne, the strongest since July 29, 2011, before reversing. It fell 0.2 percent to $2,659.50 in official open outcry trading. “It’s the time of year when Chinese mining of zinc and lead comes under a lot of pressure when Inner Mongolia shuts down for winter,” said Colin Hamilton, director of commodities research at BMO Capital Markets. “It’s clearly tightened up the concentrate side of the market and that’s feeding through into LME pricing.” Shortages of lead concentrate in China have become so severe that treatment charges — the fees that smelters charge to turn ore into metal – have skidded to zero or negative levels in some cases, he added. * DOLLAR: Metals were pressured by a firmer dollar index as the U.S. currency reversed earlier falls against the euro as traders took some profits ahead of U.S. non-farm payroll numbers. A stronger dollar makes commodities priced in the greenback more expensive for buyers using other currencies. * ZINC/LEAD SPREAD: The gap between sister metals zinc and lead were expected to continue to narrow with lead seen extending gains on shortages and zinc pulling back slightly since it had already had a strong rise, Hamilton said. The premium of zinc over lead hit the highest in over a decade at $948 a tonne on Monday and has since retreated to $875. * LEAD TIME SPREAD: The premium of cash lead over three month lead rose to $21.50 a tonne by Thursday’s close, the highest in over a month, indicating a shortage of material for immediately delivery. * COPPER: Three month LME copper, untraded in official rings, was bid down 0.1 percent at $7,109 a tonne, retreating from the highest in a week at $7,188.50. Copper has the smallest speculative long position of the LME complex at 4.3 percent of open interest, according to Alastair Munro at broker Marex Spectron. * TIN: LME tin bucked the weaker trend and added 0.8 percent to $21,570 a tonne in official trading after LME on-warrant inventories – those not earmarked for delivery and therefore available to investors – slid 16 percent to 1,155 tonnes, very close to the record low of 1,125 tonnes seen in November 2016. * PRICES: LME aluminium traded unchanged in official rings at $2,225 a tonne, zinc was bid down 0.9 percent at $2,659.50 and nickel traded 1.4 percent weaker at $13,810.