Other stories in "Beaches & rock-picking"

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

Agate Central

In Moose Lake State Park, an interpretive center caters to rockhounds.

To some people, nothing is a finer destination than the dusty gravel pits around Moose Lake in northern Minnesota.

A billion years ago, when fresh lava was cooling around what is today Lake Superior, dissolved minerals flowed into gas bubbles that had formed on top layers. Other minerals coated the first layers, some red from iron or white from calcium, and over time heat and pressure squeezed them into stone.

Then, the glaciers came, fracturing the surrounding rock and freeing the agates. Pushed along by ice, they were tumbled, polished and eventually dumped along with other glacial rubble.

Carlton County is on the rim of the basin that once held Glacial Lake Duluth, and its gravel pits have drawn rockhounds for years. Now, agate hunters also can visit the  Moose Lake Agate and Geological Interpretive Center at Moose Lake State Park, just off Interstate 35 on the way to Duluth.

Naturally, it contains a magnificent collection of Lake Superior agates, the Minnesota state gemstone. Like snowflakes, no two are alike. Some are classic red, with wavy circles of white; others are the gray shades of a rainy day or colored with golds, greens and purples. One bears the number 8 in concentric layers of orange and white; another bears the image of an owl.

Wall exhibits explain agate formation and other geological history. In the "Rock Around the Clock"' exhibit, clocks set between noon and midnight show how and when Minnesota formed. The clock already is at 10:30 p.m. by the time ore is deposited on the Iron Range and lava cools on the North Shore; by the time man appears, it's already 11:55 p.m.

Admission is free to anyone with a state-parks vehicle pass; otherwise, it's $7 per car. At the desk, park rangers hand out maps of nearby gravel pits that are likely to hold agates.

(For good hunting, bring gloves, a bag, tongs and a spray bottle full of water with which to spritz likely looking rocks; the best time to hunt is early or late on a sunny day, when the sun's rays slant across the rocks. See How to find an agate.)

Agate Days on the third weekend in July is a particularly good time to visit Moose Lake. The Carlton County Gem & Mineral Club holds a free rock show  at the high school and sponsors the annual Agate Stampede, when tons of gravel are dumped on a downtown street and rock hunters are invited to pick through the rock for 350 pounds of agates — and $300 in quarters. See Agate stampede.

Festivities also include Art in the Park in City Park, with entertainment and children's games, and a steak fry from 3 to 8 p.m. For more information, contact Moose Lake at 800-635-3680, www.mooselake-mn.com, or the agate center at 218-485-5420.

Last updated on June 4, 2008