Property, Plant, and Equipment (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2010
Property, plant and equipment, net [Abstract]
Property, plant, and equipment, gross	$ 543,955	$ 307,787
Less accumulated depreciation, depletion and amortization	(111,194)	(77,810)
Property, plant, and equipment, net of accumulated depreciation, depletion and amortization	432,761	229,977
Depreciation [Abstract]
Depreciation expense	34,848	25,055	20,362
Depreciation expense recorded in cost of goods sold	34,083	24,330	19,912
Depreciation expense recorded in selling and general administrative expenses	765	725	450
Capitalized interest	24	52	376
Land, Land Improvements, and Land Use Rights [Member]
Property, plant and equipment, net [Abstract]
Property, plant, and equipment, gross	10,831	6,907
Building and Improvements [Member]
Property, plant and equipment, net [Abstract]
Property, plant, and equipment, gross	76,395	43,076
Machinery and Equipment [Member]
Property, plant and equipment, net [Abstract]
Property, plant, and equipment, gross	175,305	93,891
Furnaces [Member]
Property, plant and equipment, net [Abstract]
Property, plant, and equipment, gross	193,055	136,177
Mineral Reserves [Member]
Property, plant and equipment, net [Abstract]
Property, plant, and equipment, gross	55,843	0
Mine Development [Member]
Property, plant and equipment, net [Abstract]
Property, plant, and equipment, gross	4,058	0
Other [Member]
Property, plant and equipment, net [Abstract]
Property, plant, and equipment, gross	4,852	3,993
Construction in Progress [Member]
Property, plant and equipment, net [Abstract]
Property, plant, and equipment, gross	$ 23,616	$ 23,743