JOHANNESBURG (Reuters) - Diversified South African miner Exxaro said on Thursday its capital expenditure for the first half of 2015 was now expected to be 3.1 billion rand ($255 million), down 11 percent from its previous guidance in the face of depressed prices. Exxaro is especially exposed to swings in the price of coal, iron ore and mineral sands. It has already said it expects its first half headline earnings, the main profit measure in South Africa, to decline by at least 20 percent. "We continue to critically assess growth projects, taking cognisance of the timing of cash flow in order to prioritise capital accordingly," Wim de Klerk, the group's finance director, said in a statement. "The continuing downward pressure on commodity prices across the industry during H1 2015, has put a considerable strain on the group," the statement said, referring to the first half financial year ending on June 30. "We expect market oversupply conditions, coupled with low demand in our commodity portfolio, to persist in the near term which will demand more rigorous efforts at ensuring short-term survival and long-term profitability," the statement said. Exxaro's share price was down 1.20 percent to 88.39 rand at 0750 GMT, compared to a slight rise in Johannesburg's All-share index. ($1 = 12.1224 rand)