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Da Yooper's Rockhound and Lapidary Guide to

Michigan Thomsonite

A zeolite, Thomsonite is relatively widespread Copper Country mineral and is found as an amygdule filling in the basalts of Michigan's Copper country, although it is usually not associated with Copper. It can sometimes be found in seams or veins. It is one of Michigan's Copper Country minerals that is often used as a gemstone in jewelry.

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The Thomsonite Gem

The Mineral Thomsonite

Seaman Mineral Museum

Huge Thompsonite in
mine waste rock

Da Yooper's Quiz

What Mineral from the Upper Peninsula of Michigan is rapidly becoming popular in the Lapidary Arts field as a Carving Material?

What is the name of the Semi-Precious Gem Stone chosen as the Official Michigan State Gem?

The first life on earth was a Blue-Green Algae that formed what kind of Formations?

Name a highly collectible and famous semi-precious gem stone found on the shores of Lake Superior?

Thomsonites are often found in the waters and on the shores of Isle Royale and in some areas of the Michigan copper ranges of Lake Superior. Many of the old tailings of the Copper mining era have Thomsonites in them. Look for white chalky, small round or almond shape nodules in the poor rock. The problem of course is getting them out of the rock without damaging them. Sometimes they will have weathered out of the rock and can be found lying on the ground. (These usually will be soft and sometimes not much good, but occassionaly a good one will be found.)

Thomsonite Hill at Pole 30 on the road from Deleware to Eagle Harbor is famous for its Thomsonite. I have heard that the property has been sold, so check first before digging. The road cut at the crossing of Owl Creek is another place to dig Thomsonite. You will see the small white nodules that have weathered out of the rock. I have had best luck on the east side of Owl Creek. Also, check the road that goes into Copper Falls at the Y and to the left near the top of the hill. This is the same ridge as the Thomsonite Hill area.

Thomsonite specimen as a rule, are quite small. A little finger nail-sized stone with good radiating pattern can be considered a nice specimen. Thomsonite larger than this possessing a good radiating pattern are extremely hard to find.

Be sure to visit our Auction site for Thomsonites.



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