(MONEY Magazine) – CRATER OF DIAMONDS STATE PARK Murfreesboro, Ark.; 870-285-3113 ($4.50; $2 for children). It's the only diamond mine in North America that's open to the public.

STERLING HILL MINING MUSEUM Ogdensburg, N.J.; 973-209-7212 ($9; $8 for seniors; $6 for children). On this two-hour guided tour of a former zinc mine, visitors can see the zinc glow in the dark under ultraviolet light.

QUEEN MINE TOURS Bisbee, Ariz.; 520-432-2071 ($10; $3.50 for kids seven to 16). Don a hardhat and carry a miner's lamp on a 75-minute walking tour of a copper mine that reaches 1,800 feet into a mountain.

THE NATIONAL COAL MUSEUM West Frankfort, Ill.; 618-937-2625; 618-937-2481 on weekends ($10; $8 for children). This one-hour tour of the only vertical-shaft coal mine in the world that's open to the public takes visitors 600 feet underground.

UNDERGROUND GOLD MINERS MUSEUM Alleghany, Calif.; 530-287-3330 ($75; children under 12 half-price). This full-day tour of California's oldest gold mine is offered by reservation only.

--PATRICE JOHNSON