Don Gerig’s daughter was five years old when she began picking up “pretty rocks” in the gravel driveway of their home in Canby, Oregon. The cardiac physiologist and father of two was happy to take her on adventures along nearby riverbanks to look for treasures like agates, petrified wood, and jasper.

“The more she became interested in it, the more we would make time to go,” says Gerig, who offers rockhounding advice on the site Rock Seeker.

Some five years later (and now living in Texas), they’re full-fledged “rockhounds,” a term used in the United States and Canada to describe a hobbyist who collects rocks, minerals, gemstones, and fossils. An easy activity for kids, rockhounding is also a fun outdoor