Most towns in the Colorado Rocky Mountains bear nostalgic reminders of gold-mining days—crumbling pit heads, a few grizzled old-timers and fading memories of prosperity; such a town is Idaho Springs (pop. 1,480), 45 minutes west of Denver. But few of its inhabitants have seriously prospected for gold in years.

Not, that is, until David Mosch, a taciturn 14-year-old junior geologist digging away on vacations and after school, discovered what the local assayer calls "the best find that's showed up around these parts in more than 40 years." If early tests are correct, the vein could yield as much as $3.5 million in gold ore.

The son of a former Beech Aircraft worker and a mother who is a graduate of the Colorado School of Mines, David and his sisters, Cindy, 15, and Sue Ann, 11, have long had the "mining bug." Much of their inspiration came from tales of David's grandfather, Rudolph Gerhardt von Mosch, who walked all the way from New York to Colorado in the 1870s in search of gold. (He didn't find any, but that part of the story never bothered the kids.) For years David has been reading up on geology and asking for odd birthday gifts like hard hats and head lamps. On his 11th birthday David got the crucial prospecting chisel and hammer and predicted, "I'm going to find a gold mine."

He had plenty of land to prospect. Over the past seven years, the Mosches have been buying up some 200 old mining claims, usually for little more than back taxes, confident not only that gold prices would spiral but that they would someday find the precious stuff. But it wasn't until last September that David, working alone, found some interesting samples on a hillside close by what had once been a rich mine. He took them down to a stream to pan. Ignoring his dad's assurance that it was only old mine scraps, David took the samples to the town's only remaining assayer, George Treder, who verified that young Mosch indeed had struck gold. "The old-timers probably walked on that vein a thousand times," says Treder, "and never knew what they were standing on."

David's father immediately dubbed him "Midas" Mosch, but David is not counting his nuggets until they're mined—and that can't happen until the family lays in the jackhammers, compressors and other costly equipment needed to remove the ore. Having turned down offers of help from big mining firms who "ask too much in return," the Mosches plan to go it alone, and already have a head start with $20,000 worth of second-hand equipment.

Meanwhile, David is sticking to less glamorous work—earning money by shoveling his neighbors' snowy walks. One quandary remains unsolved as yet: how to respond to the marriage proposals he has been receiving from young ladies who think Midas is a pretty good prospect.