Property, Plant and Equipment

3 Months Ended

Mar. 31, 2022

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment

5.Property, Plant and Equipment

(in US$ thousands)	March 31, 2022		December 31, 2021
Land	$	28,286	$	27,853
Buildings and improvements		90,569		88,079
Plant, machinery, mining equipment and transportation vehicles		987,523		963,272
Mineral rights and reserves		374,326		374,326
Office and computer equipment		8,908		8,718
Mine development		583,828		566,201
Asset retirement obligation asset		75,498		75,215
Construction in process		62,746		42,055
		2,211,684		2,145,719
Less accumulated depreciation, depletion and amortization		786,105		748,356
Net property, plant and equipment	$	1,425,579	$	1,397,363