Category Archives: Rock Hunts

The Hottest Item in the Keweenaw

Most rockhounds flock to Michigan’s Keweenaw Peninsula to find copper, but there are many other rocks and minerals that are much more rare. Any rocks and minerals that were not native silver or native copper were thought of as “Trash” and ended up on the mine rubble piles. Today we are aware of these rare treasures and dig through these old piles to find them. Unfortunately many of the spoils piles have been hauled away for fill or crushed and put under roads. Just imagine the treasures that could be found under the pavements in the Keweenaw!

I found this one inch beauty within minutes of sitting down to dig. I just had to pluck it out with my fingers.

The current hottest gemstones in the U.P. are copper-included agates. Copper has replaced some of the banding in these agates. They are generally pink and often include green. These agates are found only in a few of the mine spoil piles here in the Keweenaw, and I do not know of any other place in the world where you can get them. They generally sell at premium prices (if you can find them). Some of these agates do not include copper, but are rare none-the-less just because they are associated with the copper mines.

Chris "slams" a rock containing agates.

The business end of Chris' slammer.

There are two ways you might find these rare beauties. One is finding a “floater”, or an agate nodule that has broken free of any matrix. On a huge pile of rock, you could wish for a better strategy. The second way to find these agates is to find a rock with nodules and break the rock open to expose the usually small agates. The agates can be easily fractured, so care and a lot of finesse are required to extract them. Yes, they do show up on a sensitive metal detector.

My friend Chris has a custom built “slammer” that has a chisel on the end and virtually “slams” the rock apart. However, most of us break the rock with a heavy hammer and a strong arm. One rock I found and Chris broke open contained several copper agates, but it took some time and effort to get them out. A couple agates were sacrificed in the extraction, and Chris somehow bisected one agate perfectly in half.

Those that know (me) know that if I cannot make a piece of jewelry from a rock, I probably don’t need it. I am not a specimen collector, but I sometimes find specimens, and usually keep them for barter. I found a few “traders” already and look forward to a few more as the week goes on. I think that another Copper included agate hunt may happen tomorrow. I really had fun today.

Two perfect agate halves.

They used to have convicts break rock as punishment, and we were out there doing it for fun. But we did get to leave at our choice, just about lunchtime! Smashing with the crack hammer is serious work, and Bonnie’s arm is still sore. I think IF I can keep her hammering for a few more days, perhaps her arm muscles will strengthen (good luck with that, Don).

By the way, Chris found the largest agate today, but Bonnie was a close second.

Prehnite Adventure

Monday, August 8, 2011

When you’re rock hunting you don’t always know how good the pieces are that you have found. But I spotted a promising prehnite piece today while “driving by”, that I think might be a highlight. Here’s what’s been happening.

The famous (or infamous) lift bridge separating Houghton and Hancock.

We arrived and got settled at the Houghton Campground last Thursday. The campground that the City of Houghton owns has 22 campsites for non-tent camping located right on the channel. This is a very scenic area and it is wonderfully tranquil with the occasional boat or jet ski traveling by. The channel bisects the Keweenaw Peninsula and is a shortcut from the east side of the peninsula to the west side.

Ships can pass thru the channel and when they do the lift bridge is hoisted, causing what the locals refer to as a “traffic jam”. We have been here when the lift bridge got stuck open and it really causes havoc. There is no other way to the north and the hospital is on the Hancock side, so if there is an emergency on the Houghton side (South) there is no way to get across except by boat.

U.P. Thomsonite is really ugly, but surprises await inside the ugly shell.

Today we headed out seeking U.P Thomsonite (which is pink and green Prehnite). This makes wonderful jewelry and often shows chatoyant “eyes“. When you find the stones, they are an ugly brown or bleached white and you cannot know what is inside until you cut the rind off. Picking up the right white/brown stones is the tricky part! Lots of calcite and granite show up as little white stones, but they are not of interest and I had to keep throwing them out of Bonnie’s bucket!

I'm looking for the eroded out Thomsonite.

We were with our friends Chris and Crystal. Prehnite fills voids in basaltic material, that over the years rots away and the Prehnite nodules drop out. You can dig for them in the rotted basalt, or sometimes find an eroded bank where you can simply pick them up. We filled a small bucket in short order from mostly eroded stones. We said goodbye to Chris and Crystal and decided we were done hunting for the day.

But, before we went back to the RV, I decided to explore an old logging road. I poked my head out the window, hoping to see a large agate. Chris got a big one today, and I was hoping to catch up. I saw a large seamed rock in the road and dug it up. A fantastic large seam of eyed Prehnite appeared in the rock. This was the find of the day and I think it will make some great jewelry.

A wonderful Prehnite seam.

While hunting today we found good patches of wild raspberries and Thimbleberries. No bears were about so we ate our fill. YUM!

We have not decided what is on tomorrow’s agenda yet, but we will keep blogging on our adventures here in the Keweenaw. The weather here has been ideal in the mid-70’s, but our best hunting is in the rain, so we are hoping for some soon. It has been very dry here all summer, but there was a nice shower the other night. That’s all for now.

A Most Unusual Rock Hunt

This is not the Favosite I donated to the Seaman Mineral Museum, but is a museum grade "feathery" fossil.

At our Grand Traverse Area Rock & Mineral Club meeting recently we had a request from someone coming to the area. He wanted information about hunting stones in this area, and about the geology. Because of glacial activity, we have an interesting mix of stone here. I will write about my rock hunt recently, because of the unusual specimens I found. I sometimes hunt in a private gravel pit, and often find really odd things that the glaciers have dragged down.

Our area is famous for the Petoskey Stones, of course, but other fossils include, Favosites, Horn Corals, Brachiopods, many other Devonian corals. Many other fossils from the Devonian Period as well as the Silurian Period appear.

Most of the Devonian fossils are calcified, but prior fossils can be the same species and are silica replacement. I love this one particular gravel pit because you never know what you will find. Once you think you have found everything, something else appears.

One time I found a fantastic Favosite specimen, so delicate I do not know how it servived 300 million years without deteriorating. The only thing I can think of is it ended up under a large boulder that protected it from water damage. Our area is primarily sand, so drainage is great. Normally the Favosites I get are round and glacial tumbled, but this particular specimen had much of its delicate structure intact. This particular specimen was donated to the A E Seaman Mineral Museum in Houghton, and can be enjoyed there.

A large Horn Coral about 7" long.

The first thing I found the other day was the largest horn coral I have ever found in the area. Into the bucket it went! The second specimen was another horn coral that was silica and contained a banded agate. I have never found anything like this and I have been hunting this location for a decade at least. What a delight to turn over a horn coral and see a fortification agate inclusion.

I also found a piece of Kona Dolomite of the Verde Antique variety, a lovely green Dolomite with lines of white similar to what you might see in Marble. I was amazed that this soft material survived a glacial push from the Marquette area.

I have also found Datolite and copper-included rocks at this gravel pit in the past. These were carried from the Keweenaw Peninsula. Pudding Stones are also not uncommon, and these came from the Sudbury, Ontario area. I found only one on this particular rock hunt, but it was a beauty.

Pudding Stones can be quite large. These are just babies!

Pudding Stones are red jasper and other igneous pebbles that have been “stirred” around in a white quartz matrix. The quartz is generally slightly porous and is difficult to obtain a high shine on it. These Pudding Stones on occasion contain banded agates.

People often ask me where they can find Petoskey stones, and although I do not often give away my secret spots, or areas on private property where I exclusively have permission to hunt, I can readily state IF it rains the finest Petoskey stones can be found on the back roads. Just find a dirt road and look, especially on the edge. Look in the road cuts, and washed out areas also. I guarantee you will find some nice stuff. I have seldom hunted Petoskey stones on the beach in recent years. The gravel pit stones are so much nicer. Stones from the roads have clearer patterns, and are generally much nicer. You may even find the rare pink Petoskey Stone if you are lucky. Let me know if this was a valuable tip for you.

My prize of the day was a fortification agate in a fossil. The first one I have found in 15 years from our area.

The beach rocks get really picked over so in general they are not as pristine as road rocks. Road rocks, on the other hand, are not picked over. Also the road commissions plow when the roads are wet. If you get lucky and find a freshly plowed and washed road, you can find a bucket of stones in short order.

Don’t just look in the Petoskey area. Spread out. Find someplace where no one has hunted. This is the best tip I can give anyone. Enjoy your hunting!

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?

p81901093

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.

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.

p4190021

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 22^nd as I write this and we had snow again last night. When will the winter end?

First Petoskey Stone Hunt of 2009

Living in northern Michigan is sometimes harsh, as it has been this winter. We have officially had snowfall for 7 months in a row. This is April 18^th and there are still some snow piles scattered about.

On April 3^rd Bonnie and I made a trek out for the first Petoskey Stone hunt of the year, to one of the private gravel pits we hunt . We did not expect much as it was dry, but we were honestly stir-crazy and wanted to get out. Normally we hunt Petoskey stones in the rain because they show up better.

I checked one of the streams from the melting snow and discovered a few small stones in the clear cold water. Good thing for the gem scoop as I would not have relished putting my hand in that cold water to retrieve a rock. Bonnie picked up a few right out on the flat ground of the pit. This time of year the stones are clean and stick out well on the washed sand.

It did sprinkle a little, which helped find more stones on some of the gravel piles. I checked the rock falls (These are stones which eroded out over the winter and fell to the bottom of the steep gravel banks), always a good place to look. I found a good quantity of nice stones in these falls including two high-quality pink Petoskey Stones. We also found a nice Puddingstone, which is not native to our area, but was brought here by glaciers from Sudbury, Ontario which is 150 miles away. p4190023

We are awaiting a good rain so we can go out and find greater numbers of stones.

My best find of the day was a softball sized and flawlessly-patterned beauty. I’ll probably polish that one and sell it with a tripod stand. We ended the day with about 35 pounds of really nice stones, an excellent first hunt.

I’m happy the winter is over and a beach hunt is scheduled for next week. I’ll keep you informed.