CONDENSED CONSOLIDATED STATEMENTS OF INCOME AND RETAINED EARNINGS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 01, 2016	Oct. 03, 2015	Oct. 01, 2016	Oct. 03, 2015
CONDENSED CONSOLIDATED STATEMENTS OF INCOME AND RETAINED EARNINGS
Net sales	$ 37,647	$ 36,165	$ 114,596	$ 101,715
Costs and expenses:
Cost of sales (exclusive of depreciation, depletion and amortization)	29,609	29,257	89,899	82,620
Depreciation, depletion and amortization	607	640	1,897	1,937
Selling and administrative	5,527	5,464	17,406	16,001
Charges related to cessation of mining an aggregate deposit	632		632
Gain on disposition of property and equipment	(89)	(161)	(281)	(220)
Total costs and expenses	36,286	35,200	109,553	100,338
Operating income	1,361	965	5,043	1,377
Interest income	285	9	310	28
Interest expense	(83)	(111)	(316)	(327)
Other income, net	16	43	41	70
Income before income taxes	1,579	906	5,078	1,148
Provision for income taxes	537	344	1,727	436
Net income	1,042	562	3,351	712
Retained earnings, beginning of period	63,792	60,220	61,483	60,070
Retained earnings, end of period	$ 64,834	$ 60,782	$ 64,834	$ 60,782
Basic and diluted income per share	$ 0.62	$ 0.34	$ 2.01	$ 0.43
Average shares outstanding (in shares)	1,672	1,662	1,669	1,661