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Sauk Rapids rock hound

 Man has been collecting agates for 20 years

   Lyndon Johnson’s love of rock-hunting began early in life when he learned about agates from his grandparents and parents. Johnson, who lives in Sauk Rapids, said collecting agates didn’t become a passion of his until his own two daughters got old enough to go on walks with him. Then it became a family hobby. He has been collecting them for nearly 20 years now and he has one of the world’s largest personal collections of Lake Superior agates. That translates to about 900 pounds of agates. He has found most of them in Central Minnesota and he’s proud of the fact that he’s never bought one. In response to the question about how his collection got that large, Johnson said, “Once you find one, you want to find more. You’re hooked.”

Lake Superior agates are the oldest agates in the world and are sought after by rock enthusiasts. In 1969, the Lake Superior agate was chosen as Minnesota’s official gemstone.

Johnson recently spoke to the Breakfast Club at Stearns History Center Museum and Research Center. He has written a book about Lake Superior agates and he gives presentations to groups at schools, libraries and city halls. His collection was recently on display at Benton County Historical Society.

Lake Superior agates were formed over a billion years ago, following a period of lava eruptions in the area of Lake Superior. Iron, quartz and other minerals were deposited into the lava in concentric layers creating agates. The layers give the agate the circles which look like rings on a tree. Ten thousand years ago, erosion and glacier movement caused the volcanic rock to break down and be carried away from the Lake Superior region to areas throughout Minnesota and into Iowa.  “The reason why Lake Superior agates are so sought after by people all over the world is because they are so diverse. There are no two alike,” Johnson said. He explained it’s because Minnesota has such a variety of minerals like gold, copper, iron and diamonds.

Johnson is frequently asked: What is an agate and how does it differ from another field rock? “An agate is a gemstone,” he said, “ and to be considered a gemstone, it will be translucent. When you look into it with a magnifying glass or jeweler’s loupe, you can see into it. If you can’t see into it, it’s not an agate.”  Agates don’t always have lines. They can be a solid color. Agates are also dense, whereas a more common rock such as chert, is more porous. He calls chert an “agate wannabe.” When in doubt about whether or not a rock is an agate, Johnson’s advice is to pick it up and bring it home. He washes each rock with soap and water and then inspects it using a 10-powered jeweler’s loupe under natural light. Artificial light does not work as well. A jeweler’s loupe is good for seeing small details more closely and you can get them for under $10.  “If you are a rock hound, get a jeweler’s loupe,” advised Johnson.

He uses Original Armor All on cleaned-up rocks to bring out the color and to make them look natural. “It beats other oils and doesn’t make them slimy.”

Johnson said that wherever there may be rock can be a good place to hunt. He has found agates on roads, in fields, by lakes and river’s edges, in gravel pits, at construction sites, in the backyard… “You never know where you will find one,” he said. “I’ve walked a field for 3 ½ hours and gone back the next day for another 2 ½ hours and not found anything. On another field, where I wondered if it was really worth it, I took two steps and found one.” He likes to hit the fields before spring planting begins and he said last spring, with its warmer-than-usual temperatures, was his best spring ever. He added that he respects farmers by always asking for their permission before entering a field.

It takes some practice to become successful at agate hunting. You have to train your eyes on what to look for and when to look. Johnson, a marathon runner, has discovered agates while running. “When a rock is dusty and dirty, you can’t always tell if it’s an agate. So, when in doubt, dig it out,” he said. “I have plenty of junk rocks under my deck.”

The largest Lake Superior agate ever found weighs 34 pounds.   Johnson’s largest agate is a ten pound Crazy Lace Moss agate which he found after a storm in July, 2003. He wasn’t certain it even was an agate until he dug it out and washed off the mud. He was overwhelmed with excitement when he realized what he had found. His “treasure” sat on the kitchen table for the next couple of months. In 2010, Johnson found a 2 ¼ lb. eye agate, the largest eye agate ever found. Eye agates, which are extremely rare, have perfectly round bands which look like eyes on their surface. They typically weigh only a few ounces.  In his 20 years of collecting, Johnson has collected about five pounds of them.

When asked if he is like a fisherman who won’t disclose exactly where he caught a fish, Johnson said he does give up some details about where and when he found an agate. This information and photographs of his collection are included in his book, Lake Superior Agates, What to Look For, Lyndon’s Story.  “There will come a day when I won’t remember the details myself,” he joked, “ so I keep records of them. My collection will go to my daughters some day.” As far as having a favorite agate, he said, “I can’t just pick one.” There are stories associated with many in his collection. His cousin gave him the nickname “agate magnet” after he picked up a rock while tubing on the Platte River near Royalton in 2004. He was dragging his hand on the river bottom, looking for agates when he grabbed onto and pulled up a 1¼ pound beauty.

Johnson does not buy or sell agates. People ask him all the time what an agate is worth. “I’ll give them my opinion,” he said. “ If you want to sell, you can look on-line or go to a rock shop or check the newspaper. But to get top dollar, go to the rock and mineral shows. At the biggest shows, people come from all over the world looking to buy Lake Superior agates. Then they’ll go back home and sell them for more money.” He recommended a show in Moose Lake and a larger show held in Hopkins.

Some hobbyists cut and polish the agates and some make jewelry. “That’s fine if you want to do that. It’s your choice,” Johnson said. “I can’t slice them personally. It’s rare to find them whole.”  He recommended face polishing if you want to take one edge off and get an idea of what is inside. The rest of the stone is left in its natural state.

Johnson’s agate collection is displayed at the Benton County Historical Society each year during January and February and he gives group presentations throughout the year. He welcomes questions from other collectors. Any one interested in contacting him or ordering his book can email him at lyndondj1255@

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