CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Revenues
Lime and limestone operations	$ 36,428	$ 38,096	$ 107,910	$ 103,626
Natural gas interests	506	554	1,695	1,490
Total revenues	36,934	38,650	109,605	105,116
Cost of revenues
Labor and other operating expenses	23,142	24,064	70,447	67,603
Depreciation, depletion and amortization	4,240	4,017	12,530	11,855
Total cost of revenues	27,382	28,081	82,977	79,458
Gross profit	9,552	10,569	26,628	25,658
Selling, general and administrative expenses	2,657	2,482	7,595	7,213
Operating profit	6,895	8,087	19,033	18,445
Other expenses (income)
Interest expense	56	63	174	185
Other income, net	(261)	(115)	(665)	(238)
Total other expense (income)	(205)	(52)	(491)	(53)
Income before income taxes	7,100	8,139	19,524	18,498
Income tax expense	1,433	2,058	3,959	4,664
Net income	$ 5,667	$ 6,081	$ 15,565	$ 13,834
Net income per share of common stock
Basic (in dollars per share)	$ 1.02	$ 1.09	$ 2.79	$ 2.48
Diluted (in dollars per share)	1.01	1.09	2.79	2.48
Cash dividends per share of common stock (in dollars per share)	$ 0.135	$ 0.125	$ 0.405	$ 0.375