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"Minnesota's Gemstone"


Thomsonite was created from lava flows of the Keweenawan Period, over 600 million years ago. Gases trapped within the lava and seams between the lava flows turned into hollow pockets when the lava hardened. Over hundreds of thousands of years, these hollow openings filled and solidified, forming Thomsonite. 

The unique combination of volcanic activity and certain chemicals and minerals is responsible for why the gemstone formed in this location along the North Shore. 

Thomsonite is a mineral belonging to the zeolite group of minerals, which has over 35 different recognized members. Thomsonite is one of the rarer zeolites. It forms tight acicular radiating clusters and sphericules as well as some blockier crystals and is found in the vesicles or bubbles of volcanic rock, as are most other zeolites. 


Where to Find Thomsonite

Thomsonite can be found locally on the beaches between Lutsen and Grand Marais, on Isle Royal, Michigan and near Saxon Falls and the Montreal River Gorge on the Keweenaw Peninsula in Michigan. The color and texture of Minnesota’s Thomsonite makes it unique as gem-quality stones are found only in a limited area of Lake Superior’s shoreline about 5 ½ miles southwest of Grand Marais. Thomsonite Inn is located in the middle. 

Thomsonite is also found in the Kilpatrick Hills of Scotland; Northern Ireland; Saxony, Germany; Russia; the Faroe Islands; Kern County, California; and Cape Lookout, Oregon. 


Pure Thomsonite is snow-white and sometimes translucent. Other compounds such as ferric and / or ferrous iron or copper are responsible for the various colorations within the gemstone. Commonly found colors are pink, tan, white, red and brown. Those with green, gray or black backgrounds or green eyes are the most highly prized and least frequently found. 

History & Background

Dr. Thomas Thomson, for whom Thomsonite is named, first described the mineral in 1840, after finding it in the Kilpatrick Hills of Scotland. 

The Minnesota Geological Survey was established in 1873 and headed by Newton Winchell, who taught in the winter and conducted surveys during the summer months. Two of his students, young professors from the University of Minnesota, S.F. Peckman and C.W. Hall, spent their vacation in 1879 along the north shore of Lake Superior studying rocks. A report they published in 1888 is the first printed reference to Thomsonite. 

During the turn of the century, Hans Bernard Larsen, a Norwegian immigrant who came to Grand Marais in 1888, sold Thomsonite in a summer tent along Good Harbor Bay. By 1924, the American Exploration Company owned much of the Thomsonite-laden property. 

In 1942, Harlow Tyschen bought Lake Superior shoreline and began to mine Thomsonite. He sold his property in 1974 to Anita and Jack Brust and formed Tybrus Gems to mine the stones.  Some of their prize gemstones are on display in the Office/Jewelry Shop. 

Maurice and Tania Feigal bought 500 feet of shoreline to build Thomsonite Beach Resort in 1961, where they mined and sold Thomsonite jewelry until 1998. For 36 years they were well known to North Shore visitors for their passion as “rockhounds” and lapidary experts. They loved to share their knowledge, make beautiful silver or gold jewelry while offering lakeside accommodations which soon became treasured memories shared by generations of guests.

The Feigal’s sold the resort in 1998 to Matt and Vicki Geretschlaeger who operated it until November of 1999.  It was then purchased by Lee and Scott Bergstrom. Lee is a North Shore native and is the granddaughter of Isak Hansen. Lee and Scott owned the resort for 22 years and took immaculate care of the property. They welcomed hundreds of guests and treated them like family. In 2021, Thomsonite Inn sold to Joe Swanson, another North Shore native from Silver Bay.


"Thomsonite is SO cozy. We loved our stay so much. Use of the grills and firepit made it seem like a fun community with other guests."

- Sara H.

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