Other stories in "Beaches & rock-picking"

• How to find an agate
  Beaches are pretty, but pits are better.
• 10 great beaches
  In land of lakes, it's not hard to find a place to play.
• Grand sand
  Along Lake Michigan, the Sleeping Bear Dunes are a giant playground for all ages.
• Agate Central
  In Moose Lake State Park, an interpretive center caters to rockhounds.
• Beaches of the North Shore
  Agate-hunters, storm-watchers, picnickers — they all want to be close to the edge.

Agate stampede

Every year, Moose Lake introduces budding rockhounds to the thrill of the hunt.

It's no secret there's buried treasure right here in Minnesota.

It's in every gravel pit, along every railroad track, on every beach. All you have to do is look to find a Lake Superior agate, Minnesota's official state gemstone.

And every July, agates also can be found spread over Moose Lake's main street — 350 pounds of them, some even polished, hidden along with 1,200 quarters in 4 tons of rock.

It's the Agate Stampede, centerpiece of Moose Lake's annual Agate Days, put on by the diehard rockhounds of the Carlton County Gem and Mineral Club. Children get first crack at the treasure. Then, after 10 minutes, anyone can look.

"We try to get the little kids in; of course, there are a lot of big behinds in there, too,'' says Tom Olsen of Carlton.

Carlton County, at the rim of the basin that once held Glacial Lake Duluth, is at the heart of Lake Superior agate country. Agates were created more than a billion years ago by dissolved minerals that flowed, layer by layer, into gas bubbles that formed in cooling lava. Squeezed into hard stone, they were freed from surrounding rock by fracturing and erosion, and eventually picked up and spread by glaciers.

Today, the colorful, semiprecious stones are found with other deposits of glacial debris, primarily in gravel pits, but also washed up along rivers and lakes. The distinctive, glassy bands left by silica and other minerals appear in endless variations on the agates, which makes them fun to collect — and show off.

When my kids and I went to the Agate Days show in Moose Lake High School, Stan Peterson of Cloquet took a shadow agate out of his case and showed it us.

"Because the lines are so close together, when you move it, it changes your perspective,'' he said, moving it from side to side. "It looks like water, doesn't it? It's an optical illusion.''

Peterson and his wife, Fran, live near a gravel pit and have been picking for decades; as longtime members of the Gem and Mineral Club, they contributed 25 pounds of agates to the stampede.

"We do this for the joy of picking and showing them off,'' he said.

Other rockhounds were showing pink rhodochrosite from Argentina, "crazy lace'' agates from Mexico and momsonite from Oregon, with green, blue and red splotches that looked like little watercolor paintings.

Of course, we knew we weren't going to find agates that looked like that. Margaret Maine of New Hope, helping out at a friend's stand, showed us what an agate in the rough might look like — coated with waxy, peanut-butterlike jasper, perhaps, and pitted, like a rotten potato.

"This is a really fun hobby,'' she said. "Oh, it's so exciting. The largest one I found was this big.'' She cupped her hands as if around an ostrich egg.

In downtown Moose Lake, a crowd was watching as a green dump truck spread rocks all along Elm Street, in front of the Lake Theatre. At the crack of a cannon, the children ran in, as the adults hovered nearby.

"Oh, I see one right there, 4 inches from that guy's shoe,'' said longtime collector Margret Todd of Chisago City, who nevertheless kept quiet as her granddaughters looked. "Oh, I just want to dig in.'' But eventually, little Courtney found a red half-pounder with a glassy surface, and held it up as a TV cameraman zoomed in for a close-up.

"Pretty darn good for a 6-year-old, huh?'' Todd said proudly. "I think all kids should learn how to do this.''

Then the 10 minutes were up, and bedlam set in. On one end of the street, Heidi Bailey of Lakeville was dressed for success, with long gloves, a bag slung over her shoulders and red plastic tongs and a spray bottle in her hands. When she found a likely rock, she'd spritz it with water to see if a shiny surface peeked through the dirt.

"We make it a rockhound weekend,'' said Bailey, who was camping nearby with her sister and their daughters. "It's a fun deal, and you can go up to Duluth. We've gone up the lake from Duluth, but we've never found anything. We've found more on the dirt road outside the campground.''

My daughter Madeleine, 11, and Peter, 8, didn't fare so well. Madeleine had simply picked out pretty rocks, and Peter had stuffed his newsboy's cloth bag with rocks, period. "I just wish they were all agates,'' he said glumly.

Madeleine gave one of her rocks to Lois Allen of Minneapolis, who spat on it and rubbed it with her finger. "You can always tell a rockhound; she's got dirt in her teeth,'' she joked, before telling Madeleine the rock was indeed an agate.

Allen, who once ran a rock shop and was on the committee that made the agate the state gemstone in 1969, had brought her 14-year-old daughter Nicole and two of Nicole's friends up to the stampede. Between them, they'd found a half-dozen beautiful agates, including a zebra and an eye agate. They must've been good luck; as I turned away, I looked down at my feet and saw a polished topaz agate, the size of a small arrowhead.

Then we returned to the high school for another look at the exhibits. Peter paid $1 to buy a polished agate from retired teacher Ed Bender, and 25 cents to get a handful of little ones from a gumball machine. But then Bender gave him another quarter's worth free, as well as a shiny piece of jasper. Peter was awestruck.

"I love this place,'' he said. ``That guy is super nice. Can we come back tomorrow? All of a sudden, I'm so interested in rocks.''

Voila! Another rockhound is born.

Trip Tips: Moose Lake's Agate Days

Getting there: Moose Lake is 1¾ hours north of the Twin Cities and half an hour south of Duluth

Agate Days: It's the third weekend in July. The agate show is at Moose Lake High School. The stampede is at 2 p.m. Saturday. In the first 10 minutes, children 12 and under can look in a section that's seeded especially heavily with agates and quarters.

Agate picking: See How to find an agate. Just before Agate Days, Tom Olsen, retired county buildings superintendent, asks the county to take a grader and uncover new material at the old Soo Pits, just northeast of town.

From Minnesota 61 north of town, take County Road 8 east. Take the first left after crossing the Moose Horn River and drive a mile, between two lakes. To get to Hatchery Pit, drive mile north on 61 from its junction with 8, turning onto Agate Road (it's between Sunset Memorial Cemetery and some storage sheds). The pit is on the left.

If you want to look on the North Shore, you'll find tips about good spots at Beaches of the North Shore.

Moose Lake State Park: There's a geological interpretive center just off I-35 that has wondrous displays of agates. See Agate Central.

Information: 800-635-3680, www.mooselake-mn.com.

Last updated on September 30, 2008