UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Income Statement [Abstract]
Revenues	$ 76,614	$ 61,656	$ 210,420	$ 167,290
Cost of sales	66,643	54,412	183,975	146,010
Gross profit	9,971	7,244	26,445	21,280
Earnings of unconsolidated operations	16,494	15,155	45,618	42,054
Business interruption insurance recoveries	0	13,612	0	13,612
Operating expenses
Selling, general and administrative expenses	19,549	16,487	57,190	49,660
Amortization of intangible assets	167	131	574	373
Gain on sale of assets	(28)	(306)	(109)	(4,909)
Operating expenses	19,688	16,312	57,655	45,124
Operating profit	6,777	19,699	14,408	31,822
Other expense (income)
Interest expense	1,087	1,386	4,805	3,808
Interest income	(708)	(1,084)	(2,343)	(3,249)
Closed mine obligations	478	463	1,454	1,389
(Gain) loss on equity securities	(284)	(442)	237	(1,219)
Gain on settlement of excess funding liability	0	0	(3,590)	0
Other, net	247	244	767	160
Other (income) expense	820	567	1,330	889
Income before income tax (benefit) provision	5,957	19,132	13,078	30,933
Income tax (benefit) provision	(7,297)	3,497	(8,336)	4,756
Net income	$ 13,254	$ 15,635	$ 21,414	$ 26,177
Earnings per share:
Basic earnings per share (in dollars per share)	$ 1.78	$ 2.14	$ 2.89	$ 3.55
Diluted earnings per share (in dollars per share)	$ 1.78	$ 2.14	$ 2.87	$ 3.54
Basic weighted average shares outstanding (in shares)	7,454	7,312	7,415	7,383
Diluted weighted average shares outstanding (in shares)	7,454	7,312	7,449	7,395