INVENTORIES: (Tables)

12 Months Ended

Dec. 31, 2017

INVENTORIES:

Schedule of inventories

	At December 31,
(in millions)	2017		2016
Inventory, current:
Metals at average cost:
Finished goods	$	48.8	$	130.5
Work-in-process		308.0		231.6
Ore stockpiles on leach pads		320.9		310.9
Supplies at average cost		364.2		337.4
Total current inventory	$	1,041.9	$	1,010.4
Inventory, long-term:
Ore stockpiles on leach pads	$	977.4	$	806.9