SAHUARITA — The Asarco Mineral Discovery Center, a tourist attraction south of Tucson, shows guests how big things get in Arizona.

Big wheel at Asarco Mineral Discovery Center. Photo Credit: Sam Lowe

The center is affiliated with the Asarco Mission Mine, an open-pit operation that has been around since 1911. The hole measures more than 2.3 miles long, 1.76 miles wide, nearly a quarter of a mile deep and covers more than five acres. All that makes it the fourth-largest pit in the nation, and it’s still growing.

The center hosts about 30,000 visitors per year, and hosts five tours of the mine every day. They take guests to a spot overlooking the mine, which is the best place for taking pictures of the pit but a good shot requires a wide-angle lens because the hole is so big it won’t all fit into a point-and-shoot camera.

The tour bus also stops at a site where the riders can climb onto a 7,600-pound tire that stands 11-feet-8. It’s from one of the huge ore trucks that can haul 320 tons at a time. Another stop lets passengers watch rock being pulverized into more manageable powder.

The tour costs are minimal and reservations are recommended. For information, call 520-625-7513 or visit Asarco Mineral Discovery Center.