Swiss multinational natural resources company Glencore PLC reported a drop in production of several commodities in the first half of the year compared to the same period of the previous year. Glencore said on Tuesday said it produced 462,600 tons of copper from its own sources in the first half, 5% lower than 488,000 tons in the year-ago period. On a like-for-like basis, own sourced copper production was 2% down from last year. Own sourced cobalt production declined 27% to 15,900 tons, zinc production dropped 4% to of 417,200 tons, nickel production was down 5% to 44,200 tons, attributable fer…