"Thomsonite is an uncommon and desirable member of the zeolite group, forming in unique and interesting crystal aggregates. [...] An interesting habit of Thomsonite is as rounded, concentric bands, which are polished into aesthetic rounded stones. This form is most well-known at Thomsonite Beach at Grand Marais, Minnesota, on the shoreline of Lake Superior. It usually forms in association with other zeolites and green Chlorite. Thomsonite is named in honor of Scottish mineralogist and chemist Thomas Thomson." -  https://www.minerals.net/mineral/thomsonite.aspx

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We have a fairly large collection of Thomsonite, and  it's circular patterns of pink, black, and green make it one of the most unique local gems. As a softer stone it's best for earrings and necklaces, or rings that don't get worn everyday.