BMI Research expects prices to continue sliding for at least the next five years on rising supplies from Australia and Brazil and expectations for a surplus.
Both iron ore and diamond output rose in the first quarter thanks to a continued ramping-up of the company's Minas Rio mine in Brazil and improvements in the gem market.
The miner had to put its plans on hold because the Police Service of Northern Ireland said it cannot secure daily anti-terrorism cover for its blasting operations at Omagh gold mine.
They're pressing the company not only to accept a proposal by activist investor Elliott Management to spin off its US petroleum business, but to fully demerge all of its oil and gas assets.