Property, Plant and Equipment (Tables)

12 Months Ended

Dec. 31, 2020

Property, Plant and Equipment [Abstract]

Major Categories of Property, Plant and Equipment and Accumulated Depreciation and Depletion

The major categories of property, plant and equipment and accumulated depreciation and depletion are presented below:

	December 31,
(millions of dollars)	2020			2019
Mineral rights and reserves	$	565.8		$	571.0
Land		50.9			47.5
Buildings		225.6			218.1
Machinery and equipment		1,254.3			1,241.2
Furniture and fixtures and other		138.9			144.1
Construction in progress		41.4			35.1
		2,276.9			2,257.0
Less: accumulated depreciation and depletion		(1,237.3	)		(1,204.2	)
Property, plant and equipment, net	$	1,039.6		$	1,052.8