Then a round rock about the size of a baseball comes tumbling out of the clay. This is why. Judging by its round shape and relatively light weight for its size, my work has been rewarded with a geode, unlike any other found in the United States.
Geodes are hollow rocks lined with crystallized minerals, often in different-colored layers. And for rockhounds, Utah's west desert yields one of the world's most famous collecting spots. Because it is on Bureau of Land Management land, anyone is allowed to gather the rocks.
The geodes are filled with quartz crystals, often clear or blue, and sometimes pink. Other trace minerals make the geodes shine lime green under a fluorescent light.
The geodes formed approximately 6 million to 8 million years ago during volcanic activity when trapped gases formed cavities within rock layers.
Roughly 14,000 to 32,000 years ago, Lake Bonneville, which covered much of western Utah, eroded away the rock layers and deposited the geodes where they are today in the ancient sediments.
The geodes aren't as plentiful as they once were. Rick Dalrymple, the owner of the Rockpick Legend Co., tells stories of how rockhounds would load pickup trucks with geodes found scattered around the ground.
Now, it takes a little more work to find the prizes, but think of it as an Easter egg hunt, only this time, you'll never know what you've found until you crack it open.
The geode beds extend up into Idaho, but the Dugway site is the most concentrated area, almost guaranteed to pay off anyone who is willing to do a little digging.
"People drive from all over the country to go there," Dalrymple said. "The most colorful geodes come from Mexico, but this is one of the few places where you can collect them yourself."
Getting to the geodes isn't easy - it requires a 50-mile drive on a dirt road - so plan for a full day.
Rather than trying to beat it out to the geode beds and back, it's best if you take your time and enjoy the trip as well as the rock hunting. Antelope and wild horses can be spotted on the trip out, and because of all the recent rain, the desert looks more like a green plain than a desert right now.
The road is surprisingly well-maintained, but a high-clearance vehicle, such as a pickup truck or sport utility vehicle, still is recommended because the turnoff road to the geodes can be a bit rutted.
The geodes are found in and just below a clay layer, anywhere between 1 and 4 feet down. There are two ways of getting there - either start your own hole, or jump into one that someone else has started.
Commercial diggers use backhoes to excavate the geodes, and often their spots are a great place to start with half the work. Once you hit the clay layer, investigate a little farther down, or horizontally. If you find one geode, chances are you'll find others. Just be careful with how horizontal or deep you dig - the soil is loose, and cave-ins are possible.
If you get tired of digging, take a stroll around. The ground is littered with broken geodes that are easy to collect and often just as pretty or interesting as you'll find with hard work.
If you find whole ones, you can either hit them with a hammer to break them, or take them to a rock shop and have them cut.
How to get there: From Salt Lake City, take Interstate 80 west to the Tooele exit, then go south on Highway 36 for about 40 miles to the Pony Express Road. Turn west (right) and go 50 miles on the dirt road to the geode bed turnoff, marked with a sign. Go one to two miles up the road until you see the geode beds and recent digging.