News that China will allow the yuan more flexibility after a two-year peg against the dollar has given the mining sector a lift. Among today's top performers are BHP and Rio, which have agreed to increase iron ore royalties at all their mines in Western Australia in order to smooth the passage of their US$116bn iron ore joint venture. The deal will see rates rise from 3.75% to 5.625% for fine ore and from 3.25% to 5% for beneficiated, or lower grade, ore. The rate of 7.5% for lump ore is already the prevailing rate for most of that ore produced by BHP's projects.The best performer in the sector, though, is Connemara Mining, which has reported good drilling results from its zinc and lead operations in Limerick, Ireland.The pharmaceutical sector is lower, with cannibis-based medicine developer GW Pharmaceuticals among the fallers.The market has given a frosty reception to GW's UK launch of Sativex, a spray for the treatment of spasticity due to Multiple Sclerosis (MS). KBC Peel Hunt analyst Paul Cuddon said that details GW has outlined on the new treatment's potential sit 'at the lower end of our expectations.'Top performing sectors so far todayIndustrial Metals & Mining 5,834.31 +5.01%Mining 22,275.96 +4.47%Automobiles & Parts 3,137.68 +3.87%Forestry & Paper 4,666.15 +3.22%Oil Equipment, Services & Distribution 18,097.27 +2.55%Bottom performing sectors so far todayPharmaceuticals & Biotechnology 8,699.52 -0.30%Oil & Gas Producers 6,802.85 -0.23%Gas, Water & Multiutilities 4,109.28 -0.22%General Retailers 1,625.27 -0.05%