The JSE suffered a big drop yesterday, with mining stocks once again faring worst. The all-share index closed 1.67% down and the blue chip Top 40 was 1.6% weaker. The gold index was off 4%, banks 3.15%, financials 1.98% and industrials 0.81%.Mine counters were under intense selling pressure in response to a continuing fall in commodity prices, with platinum hitting a near seven-year low.Glencore topped the losers' board, shedding as much as 28% to R15.05 at one stage, in the process wiping off more than R60-billion of its market capitalisation. The resources index tumbled 6.05% and the platinum index dropped 7.65%.Risk assets were hard hit as weak China industrial profits data renewed growth fears.The rand weakened beyond the R14 to the US dollar level yesterday as the greenback strengthened on official hints that a US rate hike later this year is likely.Zambia's kwacha went into freefall yesterday hit by a worsening outlook for key export copper as the metal's price hit a one-month low, amid fears that mining giant Glencore might further rein in its operations in the country.The currency fell more than 17%, its biggest one-day fall on record."We have a double whammy happening, meaning copper prices continue to soften and production targets are at risk because of the Glencore news," said Kevin Daly, portfolio manager at Aberdeen Asset Management in London.Glencore's Mopani copper mine is the second-largest employer in Zambia after the government...