Oz Minerals shares slump to decade low Oz Minerals has disappointed the market with rising costs, sending its shares down. INVESTORS have dumped Oz Minerals stocks to 10-year lows after it slashed production guidance in its quarterly update. The copper and gold miner also forecast a further rise in costs in the current quarter while admitting it was only breaking even as a business in the three-month period to the end of March. Oz Minerals slumped 51 cents, or 10.6 per cent, to $4.30. They closed below $5 last week for the first time since 2003 and are down 35 per cent for the year, following a 33 per cent fall in the stock last year and 36 per cent in 2011. Production from its only producing mine Prominent Hill was now expected to be 82,000 to 88,000 tonnes of copper, down from prior guidance of 90,000 to 95,000 tonnes, the company said on Monday. Total production costs per pound of copper in the March quarter were nearly $US3.23. Copper had its worst week in 16 months last week and is currently trading at just $US3.12 a pound. Gold fell to two year lows in the same week to below $US1,400 a fine ounce, in a week that included negative economic news about global growth including China. Chief executive Terry Burgess said he was baffled by that and with near 8 per cent economic growth in China, copper was certainly the best commodity to be in. When asked if the company was only breaking even, chief executive Terry Burgess told reporters on Monday: "Certainly for this quarter, there's no question about it." The company raised cash cost guidance to $US1.65 to $US1.80 a pound from $US1.50 to $US1.65 - before including non-cash costs such as royalties. Cash costs in the March quarter were $US1.85 a pound, up from $US1.50 in the previous quarter and an average $US1.20 in 2012. It blamed that on a range of factors including lower expected copper production, the falling gold price and new international accounting standards. The production downgrade is due to a landslip at its South Australian mine that has blocked access and is not expected to be properly repaired until August. The repair is expected to cost $15 million to $20 million. A freeze on pay rises was also in place, including Mr Burgess who is on a $2.24 million package and $1.1 million in base pay. IG Markets market strategist Evan Lucas said investors were also worried about the fact that the company's new project Carrapteena was more than five years away. It is estimated to cost at least $2.5 billion and Oz Minerals may need a partner to make it happen, with Prominent Hill's current mine life having only six years to run. Production in the three months to the end of March from Prominent Hill was 20,474 tonnes of copper, down from 23,296 tonnes for the previous quarter but within expectations.