INTANGIBLE ASSETS: (Tables)

12 Months Ended

Dec. 31, 2013

INTANGIBLE ASSETS:

Schedule of major classes of intangible assets and goodwill

	As of December 31,
(in millions)	2013			2012
Mining concessions	$	121.2		$	121.2
Mine engineering and development studies	6.0			6.0
Software	12.2			8.9
	139.4			136.1
Accumulated amortization	(46.2		)	(43.8		)
Goodwill	17.0			17.0
Intangible assets, net	$	110.2		$	109.3

Schedule of amortization of intangibles in the last three years and estimated amortization for future periods

Amortization of intangibles in the last three years and estimated amortization are as follows (in millions):

Amortization expense:
2013	$	2.4
2012	$	2.2
2011	$	2.1

Estimated amortization expense:
2014-2018	$	9.1
Average annual	$	1.8