Most of my coworkers' kids pick up pretty parking lot rocks (and crystals and polished rocks out of my office free rock box) but by the time they're in their teens, other kids will actively mock them for showing interest in "nerdy" things or their parents tell them "no that's dirty, put it back outside." That, and the equipment for cutting, polishing and setting stones is expensive, loud and messy. It's not something most families with kids have access to, ergo the rocks are a fun temporary pursuit that get put back outside once they've run their course, because they never make the leap from 'collected rock' to cut and polished, or a cleaned, identified display piece, or some other form that the non-rock-inclined adult will see as worthwhile (when compared to sports, homework, socializing, etc.)
I got into rocks because my mom's friend's dad had a saw and cut thunder eggs for me when I was about 4. (This is now my saw.) And I stayed into rocks because my parents actively supported the interest by taking me rockhounding, stopping at rock shops, getting me a good hammer, etc. It took adults saying "I don't understand it but this is a worthwhile thing to do and I'm going to respect it and make an effort to facilitate your interest" for it to go from a childhood time-filler to an active adult hobby. (And they are happily warehousing my collection while I'm in co-rented company housing.)
All that to say, give your local kids permission to interact with rocks, teach them about what they find and facilitate access to information and technology that they aren't getting through schools or from their peers. It won't be everyone's thing but I bet you'll spark some long-term interest.
