Eric Brunes with some of the agates he has collected. Photo by Travis Grimler

Countless area residents have, at one time or another, walked along dirt roads, gravel pits, and lakeshores looking for our state gemstone, the Lake Superior Agate.

Ed Hoover, who once bought and sold agates at his Pine River bookstore Cass County Books, suggests that money shouldn't be the primary drive for agate pickers.

"Do it because it's something to do outside rather than watch TV," said Hoover. "Do it for pleasure and maybe you'll make some money."

According to Hoover the best places to hunt agates are freshly plowed farm fields. It is here that a person might find an agate that hasn't been crushed like those found on gravel roads or rooftops. Though this may be a good place to look, it is also a way for a person to get a lot of exercise.

"You gotta cover a lot of ground to find a few agates," explains Hoover.

Agate picking is a hobby with many benefits. Despite all the walking resulting in some healthy, outside exercise, agate picking is an inexpensive activity. In small town Northern Minnesota, farm fields are usually nearby and it certainly doesn't cost anything to look for rocks on lakeshores.

Perhaps even better, agate picking is almost universally seen as a family activity.

"We did it as kids. It's a great thing to do with your kids, and you have a chance of finding a gem," Hoover said.

Local rock hound Eric Brunes agrees that agate picking is popular, easy and a great family activity.

"That's what really started me with agates. Finding something for me to do with the kids. Finding something to do with the family," Brunes said.

Along with the benefits of agate hunting, there are some limitations.

"As far as Cass County and Crow Wing County it is getting kind of hard to be an agate picker anymore," Brunes said.

This is because of private property signs being posted in gravel pits across much of Minnesota. Owners in the state are being forced to make these gravel pits, that were once agate picking havens, off-limits due to insurance liabilities. Luckily, Brunes was able to secure permission to pick agates from a local gravel pit owner outside of Pine River.

"It is a family sport...It was a family sport years ago. It got tough. Pits are getting closed down all over the place. It's kind of taking the wind out of our sails on doing a lot of agate picking."

Since starting picking with his children, Brunes has formed a collection. According to Brunes and Hoover, agates are worth money solely because they are considered beautiful. While size, shape, and color do determine price somewhat, it is this beauty that determines the value of an agate.

"There are ugly agates, and try to sell one of those. No way," said Hoover.

But how are these beautiful gems formed? According to Rick Meyer of Pine River-Backus High School there are two theories that try to explain how these stones are made: the Single Gel Theory and the Multiple Solution Theory both say that agates are formed within basalt vesicles, or trapped pockets of air that were made while the basalt was molten lava. These vesicles are filled by heated, mineral rich water, but this is when the two theories differ. That water is either trapped until chemical reactions force the minerals within it to solidify - as the Single Gel Theory suggests - or the water deposits a layer of mineral material on the inside of the vesicle before draining and being replaced by more.

According to these theories, the different colors and banding are formed inside the agate due to trace minerals that stain it one color or another. Different concentrations of iron tend to make different shades of red that the Lake Superior agate is famous for. However, according to Meyer these colors do not truly develop until the rocks are exposed to weather and air at which time the iron begins to oxidize and turn red. Before that time the rocks are a pale, waxy white.

Lake Superior Agates are produced primarily in the area of Lake Superior, as the name suggests. Basalts there were once pocked with these gem filled vesicles. At one time the basalt became so heavily weathered that it softened. Later, years of glacial flow from north to south dragged and ground away this basalt releasing these agates and leaving behind a layer of topsoil now known as glacial till.

The till can be located from the southern tip of Lake Superior all the way to Nebraska. Using a topographic map you can sometimes follow the paths of the glaciers that left behind the till as they followed the low areas where volcanic rock weighed down the earth. Some even left behind low spots of their own. According to Meyer, locating this till is key to effectively finding agates.

For those who do decide to hunt agates for money, or even those who stumble across a prize agate, there are a few things to keep in mind. Part of what makes agates valuable is size: generally, the bigger the more valuable. However, damage to an agate can greatly reduce the value.

"Today I wouldn't recommend anyone to even put them in a tumbler," explained Meyer, "There's more value to the collectors being in the raw state versus being polished in a tumbler."

Though polished rocks have a reflective surface that some people find attractive, tumbling also results in a certain amount of the stone being eroded away. This, along with cracks and dings from other rocks in the tumbler, is considered damage, which reduces the value of the agate.

"I think it also goes kind of in phases," said Meyer. "In the past they liked the polish. Today I like mine in the raw state and just sort of hand polished."

Meyer explained that springtime is prime for hunting agates on dirt roads, lakeshores, freshly plowed farm fields and gravel pits, with owners' permission. On lake shores there are less weeds and algae in the spring. Spring showers also help to uncover dusty gems. Agates also seem to glow when the sun is at a low angle due to quartz's semi translucent characteristics, so early mornings and afternoons are the best.

For more information consult a good rock guide at your local library or find a friend with some experience and go nuts. If all else fails just go for a walk; you can't lose.