Category Archives: Michigan Stones

Bonnie’s Great Datolite

My wife Bonnie has been tagging along half-heartedly with me to Keweenaw Week for several years. She likes wearing my jewelry, but just never has found anything that got her really excited and proud. It always seemed like a lot of rock to look through, with most of it turning out to be nothing good. Those copper tailing piles are really big, and looking for the “good stuff” is a lot like looking for a needle in a haystack. And I hate her dragging non-jewelry grade stuff home and mixing it up in my barn with all my real treasures. (That barn is a whole other story. One that may never be told.)

Datolite is an elusive gemstone. We went to a mine that we’ve been to many times, hoping to find some good datolite. Of course for Bonnie this would be her first datolite, and she really had some low expectations. She’s spent hours digging holes that never gave up anything to take home. We have friends who seem to be able to just smell them and go right to them, and bring home a great story to brag about. Bonnie just wanted to find ONE. We chose to dig under some trees, figuring whatever was there hadn’t been seen in a long time. As the dig progressed Bonnie got dirtier and dirtier. That was the main thing I noticed. She made a pretty big hole, and pulled out a large chunk of rock that had two small (4-5mm) rounded white spots sticking out of one side. Now that’s the magic formula: rounded and white, so Bonnie put it in her bucket. It did register on the metal detector, so that was good too. But really, it didn’t look like much (those two small white spots are way too small for me to make jewelry with, that’s how I judge rocks).

Bonnie found one other datolite, not huge, but big enough to make jewelry from, so she was pleased with that. I got some cutting material, rock with copper running through it that should turn out pretty. We went home not too excited and I took a nap. Bonnie went to a faucet outside and began to scrub away some dirt from her rock with “twin towers” as she referred to them. The more she scrubbed, the more excited she became. A strip of white datolite began to show up on the bottom, other white rounded areas and some small copper points were poking out.p8120186

She continued to scrub off mud, finding more white nodules and got really excited. I wanted to see what the copper would really look like, so I gave it a quick acid bath. See for yourself. Bonnie’s “boring” datolite find, her very first, turned out to be a beauty that any rockhound would be ecstatic to find! This is part of the charm that keeps rockhounds coming back to the Keweenaw year after year. I expect she’ll be more excited about our rockhunts in the future. Copper and datolite nodules combined in one terrific stone clump. What could be better?

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Mohawkite

Originally named after the primary source at the Mohawk Mines (copper mines) in Mohawk, Michigan, Mohawkite is a rock that closely resembles fine gold in quartz from California.

Algodonite and domeykite are the two principal arsenides found in the Keewenaw. These two minerals when mixed with arsenian copper form Mohawkite. Mohawkite is one of them many historical names for this mixture. The Mohawk #2 as well as mines at Ahmeek were the primary source for this rock. A little know factoid is that over 100 metric tons of Mohawite were removed from the Mohawk mine between 1900 and 1901. The Mohawkite was massive in nature. p9130106

I have hunted Mohawkite on organized trips in the Keweenaw. I believe the Mohawk spoil piles are private property so make sure permission is gained before going on these piles. Mohawkite is elusive and requires some luck and a good metal detector to find.

I always treat Mohawkite with respect when working with it, always using gloves and a mask when grinding and polishing. I also change the water on the Genie and any saws I use after finishing with Mohawkite.

After the Mohawkite cabochon is polished, it is fairly docile (unless you plan to eat it!). I have been experimenting with coating the cabochon with industrial epoxy. This seals the metals against tarnish, but having said this, some people like the tarnished-natural look and prefer a natural, polished stone.

Mohawkite is an unusual and obscure jewelry material, and one of those special rocks to be found only in my favorite rock hunting location, the Keweenaw Peninsula.

I sell Mohawkite jewelry both on this website and at our art shows.

A Most Wonderful Greenstone Hunt

The location of this hunt will remain a secret other then to tell you it took place somewhere in the Keweenaw Peninsula. This took place in September 2009.
Sometimes I think we rockhounds are a little crazy to go out and bang on rocks in the hot sun and call it “fun”. I think this is what convicts in chain gangs used to do. I bet it wasn’t fun for them! Other times we are out in a downpour because this is the best time to spot the type of rock we look for.
Let me tell you about one of those trips to an old rock pile in the U.P. when it was pouring rain. Bonnie and I donned our heaviest rain gear and waterproof boots and headed to one of the old mine dumps where we had previously enjoyed some success finding Isle Royale Greenstone. Immediately we found greenstones literally “washing out” of the banks in one small area on the pile. This is when you suffer bouts of greed, amazement, and wonder.
We harvested these stones as well as finding numerous other rocks full of Greenstone that we will remove later at home by cutting or breaking the matrix. Greenstones, when found, are generally small, ugly, dark green nodules. Often I see a glint of chatoyancy in the nodule, or the nodule may be broken and you can see the pattern where the break is.
Many of the greenstones we were finding that day were over one inch and we could see good chatoyancy in the nodule. This is remarkable size considering the average greenstone is maybe half the size of a pea. Over the course of four or five hours we picked up a gallon size ice cream bucket of loose nodules and larger nodules in matrix, and another five gallon bucket of greenstone bearing basalt. Greenstones are very rare and are found nowhere else on earth except Isle Royale and in the Keweenaw. Picking up this many in one day is remarkable. In one day Bonnie and I found more greenstone than the total amount we have picked up all the previous years we have been hunting.
I expect we will never have another greenstone hunt like this. It amounted to being at the right place, in the right location, at the right time. Few hunts work out this good. Dealing with the elements and not caring; finding valuable gemstones like they were common quartz; collecting not only treasures but memories. How great this was. I wish you could have been there.
Some of these new stones will be for sale on this website in the near future.

Jeane’s Dragonfly

As a fun project I made a dragonfly pendant bead-dragonfly-11based on a design I found in one of Jessie Donnan‘s advanced wirewrapping books. The first dragonfly features glass beads for the body. I had the glass dragonfly out at a show in Michigan’s Upper Peninsula and one of our customers, Jeane, liked it. She had the creative idea that I should make another copy using Michigan’s distinctive state gemstone, the Isle Royale Greenstone. Jeane is an avid lover of Upper Peninsula rocks and minerals as I am.

I am always up to a challenge, and I immediately thought that this was a wonderful idea. I used silver beads for the eyes of the dragonfly, but made it from 14/20 gold filled wire. The trick was in finding enough greenstones in the right size and having them drilled. dragonfly I may someday make another dragonfly similar to Jeane’s, but for now she has the only one. Thanks for the great idea Jeane!

Prehnite

Sometimes I find wonderful Prehnite on the mine dumps in the Keweenaw Peninsula.

If prehnite forms in veins, as it does in the Keweenaw Peninsula, it generally associates itself with native copper. I love to find these rare pieces that make lovely jewelry, with the apple green of the prehnite surrounding the shiny copper.prehnite-with-copper1

Most of the Prehnite of the Keweenaw is vein Prehnite. In vein Prehnite one cannot notice the chatoyant needle-like crystal structure normally associated with larger non-vein Prehnite pieces such as the gemmy pieces found in Australia and other locals around the world. Feather-like Prehnite crystals are seen in U. P. Thomsonite which is actually variegated and non-variegated Prehnite. Pink, red, and green, and other color combinations can be found, depending on what minerals flowed into the vesicles and veins along with the Prehnite. Locals refer to pastel Prehnite permeated with copper flecks found on the beaches in the Calumet, and also in the Copper Harbor area as “Patricianite”. These Prehnite pebbles can be jewelry grade, and are wonderful to collect as they roll in with the Lake Superior breakers.

Prehnite is very solid, but brittle, so care must be taken when cutting it. Stay away from new grinding wheels and rough grits. Harmonic vibrations can blow apart this material.

High quality Prehnite is available from various locations throughout the world, but when you add the native copper to the Prehnite from the U.P., you can’t beat ours.

Finding and Working Greenstones

Finding a greenstone:

It is illegal to remove greenstones from Isle Royale National Park, so you will have to look in the Keweenaw Peninsula. Some of the old spoils piles from the copper mine contain greenstones. Watch for nodules dark green, ugly looking nodules within basalt. A good hint is the harder the basalt, the better and gemmier the greenstone may be. When you find a greenstone-included rock you will have to very carefully “pop out” the greenstone, careful not to lose it when you pop it out. I generally take the whole rock to an area where if the suspected greenstone pops out you may still be able to find it. Look also for a glint of chatoyancy in a chipped stone. Don’t expect any large greenstones, but maybe you’ll be lucky. Many of the old dump piles at the mines have already been crushed up and used for road fill in the Keweenaw. When I first started hunting rocks in the Keweenaw 20 years ago there were many large piles of rubble to dig through. p5250030Now many of those piles are gone, substantially depleted, or privately owned and not accessible anymore. Don’t be discouraged as there are still rock hunting opportunities available. The local rockhounds probably will not tell you their best spots, but will point you to a pile of rock that you can find something. Take your metal detector with you, if you get tired of looking for greenstone you can look for copper. You can rent one at Keweenaw Gem and Gift in Houghton if you do not own one.

Understand that the average Greenstone is half the size of a pea, and any greenstone of a large size is extremely rare. Anything over 5 grams is considered a rarity. The greenstones I feature on my website have been accumulated over a 20 year period by personally hunting them or purchasing old collections.

For every ten possible greenstones I pick up, one may be a real greenstone. The others may be basalt or chlorite balls or some other greenstone “wanabe”. Out of the good stones, one in 100 of those may be a large greenstone and solid enough for jewelry. I guess that is the reason you don’t see Greenstones on one of the home shopping networks that feature the common diamonds, sapphires, rubies, and other “jewelry store” fare. I cannot believe people spend good money on common jewelry store merchandise and are not buying really rare and distinctive gemstones instead. My wife refuses to wear diamonds and such. Of course she understands the economics of artificially inflating values by pretending they are rare (I rant about this enough, she picks up some of what I profess). Dr. Robert Proctor of the History Department of Stanford University commented on how a wonderful Lake Superior agate is much more rare than a common diamond in a keynote oration he gave at the Wonderful World of Agates symposium in 2008. If, as Proctor suggested, many agates are far more rare then diamonds, imagine how rare a one-source gemstone such as Greenstone is.

Working with Greenstone-

So now that I have vented a little and feel better I’ll continue. Cutting greenstones is also challenging. The layer of real chatoyant greenstone is often thin and you must cut the stone so as to not go through this layer and yet remove all the blemishes. Sometimes this is not possible and you have to discard the stone. Other times, I’ll hit a hollow spot; stone ruined. If you find a nice greenstone, never allow someone to cut and polish it for you that is not experienced with working with this material. I know just a handful of cutters in Michigan that really know what they are doing with greenstone. It does not take much to botch this material. Greenstone is not like any other stone when cutting it, and I personally ruined quite a few pieces when I was learning to cut it. Thousands of greenstones later I am confident in my abilities. I custom cut and polish greenstones for people that find them. As an aside, and since you have taken time to read my blog, I will tell you that there are crooks and sham artists that may try to sell you what they claim is an actual greenstone, but in fact may be a piece of basalt, prehnite, or other greenstone look alike. At least one of these sham artists operates a roadside business in the area. So buyers beware. Do some research before you buy, or buy from me. My greenstones are genuine, and I would not sell you any stone I would not be proud to own myself. I offer both fine wire-wrapped slides or pendants and polished individual greenstones that you can work with or have a jeweler craft for you.

I’m proud to say we have the largest selection of Isle Royale Greenstone on the internet, but only a small portion of the greenstones I have available are posted. If you are looking for something in particular contact me and ask. I expect to post up more loose stones in the near future.

Isle Royale Greenstone/Chlorastrolite (AKA Michigan Greenstone, Greenstone, Pumpellylite)

Michigan’s State Gem, the Isle Royale Greenstone, Greenstone Pendant with Datoliteis unquestionably one of the rare minerals of earth. It can only be found on Isle Royale National Park and in Michigan’s Keweenaw Peninsula. Greenstone is a close relative of Epidote. Chlorastrolite (translated from Greek as green, star-like stone) is actually a form of Pumpellyite. “Chlorastrolite” was adopted as Michigan’s gem March 30, 1973.

Greenstone formed in amygdaloidal pockets of Keweenaw basalts. At one time Isle Royale and the Keweenaw formed one land mass. Isle Royale was spit off from the Keweenaw when the rift that formed Lake Superior split a giant gash in the earth.

Thanks to Benjamin Franklin, the Keweenaw Peninsula and Isle Royale are part of the United States. Franklin was a member of the commission that drew up the boundaries for the Treaty of Paris in 1773, ending the Revolutionary War. Ben Franklin had heard of the rich mineral deposits in the Keweenaw and Isle Royale so he drew the boundary line to the north of Isle Royale, giving this area to the United States instead of Canada.

The mineralization on Isle Royale is exactly the same as the Keweenaw. Native copper, Datolite, Prehnite, Thomsonite, Lake Superior Agates, Epidote, Greenstones, and the same basalts are seen in both locations.

Basalt 101-

As the basalts cooled, gasses tried to escape to the surface, the bubbles becoming smaller and smaller as they rose and tried to escape from the basalt’s clutches. The basalt hardened and trapped these bubbles known as “vesicles”. Also the cooling created shrinking and cracking of the basalt. These cracks in the basalts allowed different minerals in solution to flow into the vesicles, where they eventually solidified.

Copper, silver, arsenates, and other metals also filled the cracks and vesicles, but were disseminated by rising, super heated water instead of flowing down from the surface. The vesicles that the copper and other metals filled were sometimes huge and other times just cracks or small bubbles.

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Greenstone with Datolite and Copper

Greenstone with Prehnite

Greenstone with Prehnite

Copper associated itself with other minerals including all the previously mentioned material. The variety of material, mixed in different ways, is what makes this rock hunting area so intriguing. It is wonderful to see copper running through Greenstone, Datolite, Prehnite, and Lake Superior agates. Pieces of Greenstone/copper are highly coveted by collectors and jewelry makers like myself. The few pieces I have are priceless. My wife has a ring made out of one of these copper/greenstone pieces, and I still have a couple specimen pieces. She sometimes wears the ring to art shows, so ask her if you see us. To see an example of copper with datolite, take a look at my Copper Lightning Datolite.

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Greenstone with Thomsonite

Greenstone sometimes has Thomsonite inclusions, which make for a spectacular look. (Dark, chatoyant green and dark pink together) I’m waiting to find a Copper-Greenstone-Thomsonite some day. I have seen specimens of these at the Seaman Museum at Michigan Tech.

My next post will discuss finding and working with greenstones.


Roadrunner

Snob Blog fans seem to like the unusual rocks I often make into jewelry . Here is a way cool Lake Superior Agate that I call “The Roadrunner”. Do you see the bird? roadrunner1

The agate is a somewhat unusual color for a fortification agate and when I cut it, I was surprised by this great picture in it.

Sorry this was sold to Beth (the same Beth that owns the fantastic Isle Royale Greenstone that I previously Blogged about). Take a look at my rhyolite Owl which is very unique, or The Parrot. I have wire wrapped other Lake Superior agates into slides or pendants. You also might enjoy the Crazy Lace agates pendants/slides.

If you are looking for a particular animal in a rock, you can E-mail me and I’ll keep an eye out for it. You will have to be patient as these pictures do not appear commonly. No guarantee on these requests!

The Beach Hunt

I finally got out to search for Petoskey Stones on the beach. I will confess that this particular hunt site is in the Charlevoix area, but I am sworn to secrecy on the exact location.p4190018

This was the first weekend that the snow had cleared enough in the woods to get to this area. It is very remote and requires a 4WD to get to it. I went with my best rock-hunting buddy Gary. We had great expectations of finding a good quantity of Petoskey stones as well as high quality Favosites, and were not disappointed.

It actually sprinkled continuously while we were hunting, which made the stones on the beach stand out. The water was smooth so we could also see the rocks in the water. Within a month of ice leaving the area rocks become covered in slime and moss, making it almost unhuntable (my spell check says this is not a word, but I like it anyway), so early spring is the only time to have good hunting in this area. This is a prime example of knowing when to hunt certain areas and when not to. I’m sure, for example, out west you would hunt hard in the cooler weather and not hunt the desert in the summer.

Normally we park our truck at the end of the hunting area and hike the beach back the way we came in. We take a couple empty buckets and dump any buckets we fill next to the trail we came in on, then pick up full buckets as we leave.

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Indeed it was a great hunt as anticipated. Gary and I each filled a five-gallon bucket with high quality stones. This took a couple hours. Next time we’ll take our insulated waders so we can check further out in the water for the “big” ones.

As an aside, it is April 22nd as I write this and we had snow again last night. When will the winter end?

Lake Superior Agate

“Lakers” are found as beach pebbles on the shores of Lake Superior as well as in glacial till primarily in Minnesota and Wisconsin, but also in Kansas, Nebraska, Illinois, Iowa, and throughout Michigan. They are also commonly found in the amygdaloidal basalt in the Keweenaw Peninsula and on Isle Royale National Park.

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The basic material of agate is Chalcedony, a silicon dioxide form of microscopic fibrous crystals. The fibrous makeup of the Lake Superior Agates, makes them hard and able to accept a wonderful, glass-like polish. This brittle structure also makes the Lake Superior Agate prone to cracking from thawing and freezing or being moved vast distances in the glacial till. A crack-free “Laker” is quite rare to find, and are coveted highly by rockhounds and jewelry makers.

The ancient basalts of the Lake Superior region are amygdaloidal (containing gas bubbles called vesicles) in nature. Of volcanic origin, the holes from the bubbles became filled with various minerals. Often these minerals were silica, forming agates. There are several theories on how agates are formed which can be read about in some of the books we recommend on this site.

Lake Superior Agates are most often quite small, but have been found up to 20 pounds. It is rare to find a “Laker” over one-half pound. I love to tell the story of the day I personally found six “Lakers” over one half pound.

“Lakers” can be almost any color, but reds and browns are common colors. Agates are most often banded, but can occur as tubes, eyes, moss, shadow, sagenite, plumes, and almost solid colors, often orange (carnelian).

One of the most popular and sought after Lake Superior Agates is the classic red and white “Candy-striper“. A nice “Candy-Striper” cannot be mistaken for any other type of agate.

I strive to use only fracture-free, classic banded Lake Superior Agates, as well as uncommon varieties in my jewelry. No finer wire-wrapped Lake Superior Agate jewelry can be found on the web. I think the Lake Superior Agate has always been my favorite stone.