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INVESTMENT IN MINERA SANTA CRUZ S.A. ("MSC") - SAN JOSE MINE (Details) (MSC, USD $) In Thousands, unless otherwise specified	3 Months Ended			6 Months Ended	8 Months Ended	9 Months Ended
	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Jun. 30, 2012	Sep. 30, 2012	Sep. 30, 2012
Change in investment
Fair value of investment in MSC from acquisition of Minera Andes	$ 261,186				$ 261,186	$ 261,186
Amortization of fair value increments	(1,597)	1,259	890	2,149		(3,746)
Net loss	26,343	(20,707)	(16,997)	(37,995)	37,765
Reported
Change in investment
Amortization of fair value increments		1,803	2,804	4,607
Net loss		(21,251)	(19,202)	(40,453)
Adjustment
Change in investment
Amortization of fair value increments		(544)	(1,914)	(2,458)
Net loss		544	1,914	2,458
Purchase price allocation adjustment
Change in investment
Fair value of investment in MSC from acquisition of Minera Andes	$ 261,200	$ 225,000	$ 225,000	$ 225,000	$ 261,200	$ 261,200

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