People always ask me if the stones I use are "local". Thomsonite is a stone I use that is found in ancient lava flows along Lake Superior in Minnesota, Isle Royale, and a little bit along the Keweenaw Peninsula in Michigan. It is found in a few other places in the world, but it doesn't exhibit the gem quality that is found near Grand Marais, Minnesota.
Thomsonite crystals are part of the zeolite family. Zeolite is a mineral complex created from molten lava as it pours into and reacts with the sea. As the volcanoes erupted and the lava and ash poured into the sea, the combination of the ash and the salt from the sea, as well as the lava, caused a chemical reaction, and over thousands of years certain precious minerals like Zeolites began to form.
Thomsonite is one of the rarer zeolite minerals.
The Thomsonite nodules have concentric rings in combinations of colors: black, white, orange, pink, red, and many shades of green. Some nodules have copper inclusions and rarely will be found with copper "eyes."
Most Thomsonite nodules are less than 1/4 inch. And those enclosed in basalt are extremely difficult to remove without breaking them. The pieces I have been working with are spectacular, larger specimens.
Thomsonite was named for Dr. Thomas Thomson, who 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.
If you are interested in metaphysical properties of stones, Thomsonite is related to the heart chakra and will protect you from the evil eye and psychic attacks, nightmares and other negative energies. It reflects negative energy back to the sender.