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THOMSONITE
Formed like agates through water percolation into petrified bubbles in the basalt, Thomsonite is the much rarer of the two. It is even considered a semiprecious stone by some. Jewelry made from the pink, white and green nodules can be spectacular. Geologists Rapp and Wallace call the nodules of zeolite “little bloodshot eyes.” An apt name for this rare whole amygdule with an “iris” of pale green and radiating circles or “veins” of pink. One specific lava flow spawns most of our Thomsonite. It is the 160-foot-thick Terrace Point basalt flow and it is the same formation that forms the “teeth” of the Sawtooth mountains. This is seen most easily from Grand Marais looking southwest down the shore.
How to recognize:
The radiating bands or concentric circles of pink and pistachio green are unmistakable. Whole nodules are very rare. More common is a wave-washed piece with hints of pink or green. Still more common is seeing them make duels still “in matrix” in outcrops of basalt.
Where to find:
Good Harbor Bay, a few miles southwest of Grand Marais, is your best bet. The appropriately name Thompsonite Beach, just southwest a Good Harbor Bay, is only accessible to guess of the Thompson Beach Inn & Suites. Don't miss their awesome display of fine jewelry and specimens.
