Category Archives: Michigan Stones

Blue Stone Jewelry to Die For!

A stunning example of blue stone jewelry, a Lightning Ridge opal

Gorgeous Lightning Ridge Opal

Singing the Blues might mean you have a sad tale to tell, but what about wearing the blues? Let the Blues, blue stone jewelry that is, cheer you! You will not find anything sad about this happy color.

From ancient time people have been charmed to find dark blue Lapis, or sea-colored turquoise, and have loved owning it and wearing it. Like Cleopatra or native queens, lucky women wore beautifully colored stone. A precious blue stone from another location was money in the bank for ancient traders.

Blue Stone Jewelry includes An opal pendant

Blue Angel Opal Pendant is a sparkling Boulder Opal with Mercury Mist Topaz. Will you look great wearing it?

Larimar; notice the copper in one of the cabs?

Ocean Shadows Larimar Pendant looks like the ocean waves washing up on the sandy beach. Who wants to call it Pectolite?

Two of the finest Larimar cabs I ever owned.

Here in northwestern lower Michigan beachcombers seek Leland Blue for their blue stone jewelry. A left-over product of industry from a bygone era, various colors of the blue slag glass are loved for the color they add to a beach stone hunt. Often smoky blue, it can vary in purity of color and depth of color, each appreciated by different folks. Other areas of the world also have colored glass, we saw some from Sweden at our last Tucson gem show.

Bonnie’s Centennial Blue Datolite with Copper Lightning running down the gemstone.

Another special Michigan blue stone comes from the Copper Country in the Upper Peninsula, the Centennial Blue Datolite. Currently we have the Centennial Charmer and Icy Blue pendants available.

Blue Lace Agate is a favorite blue stone for jewelry. Formed in volcanic south African areas, Blue Lace agate is characterized by close linear stripes of tones of pale blue or white. Sometimes natural druzy pockets make lovely variations, older stock can be deep blue.

The blue with white shadows of Larimar jewelry reminds me of a pristine lake where you are looking at the sunny reflections of sun on the lake. Larimar comes from the Caribbean area and it seems right that it should look so waterlike.

Beautiful Sleeping Beauty Turquoise

Turquoise is probably the most popular blue stone ever found. We have a very pure Intensive Flair Sleeping Beauty Turquoise Pendant. Other stones from Royston or Kingman have matrix incorporated in the stone color, making more interest for many stone collectors.

Dark Blue Lapis Pendant in gold fill

Another famous blue stone is Lapis. Found in mountains on the Afghanistan and Pakistan border, the political and geographic situations make it a challenging stone to get. We have several faceted dark blue pieces as well as a denim lapis heart. Pyrite is often found in Lapis stone. A stone of the ancient pharaohs, it decorated the tomb of King Tut.

Our Blue Opal Angel Pendant is an Australian opal.

Morenci Flowers Azurite/Malachite Pendant with gemstones

Close-up Azurite/MalachiteAzurite is a lovely blue stone but is not as well known. Our favorite pieces often combine with malachite and originate from our own southwest copper mines, Morenci and Bisbee being the most famous. Lasting Romance Azurite-Malachite Pendant is dressed up with some other precious gems to make a beautiful piece. Morenci Flowers Azurite Malachite Pendant is a smaller stone with various shades of blue and is also enhanced by precious gems.

And if that isn’t enough choices for you, how about the Victoria Stone which has some dressy and vibrant blues. The most popular is the bright blue like the Hues of Blue Victoria Stone Pendant, but you might also like the Indigo Bling Victoria Stone Pendant dressed up with London Blue Topaz.

Indigo Blue Victoria Stone with London Blue Topaz

Our gemstone pendant inventory goes far beyond what you see on the web. If you desire Lightning Ridge Blue opal, Kyanite, Sodalite, Dumortierite, Hemimorphite or Holly Blue Chalcedony, there’s a good chance that we can make a custom blue stone jewelry piece just for you. It might sound expensive, but it really depends on your stone choice. Go ahead, ask us!

After all that beauty, you must be over the Blues! Which blue stone jewelry is your favorite? Order today before it is gone!

Chlorastrolite or Michigan Greenstone–State Gemstone

Piles of mine waste rocks used to abound in the Keweenaw. Not so much anymore. There’s a lot of Greenstone here, but where are they?

Let’s look at some interesting tidbits about Michigan Greenstone, the state gem.

After lobbying by the Michigan lapidary community, Isle Royale Greenstone (Chlorastrolite) became Michigans Official State Gemstone on February 21, 1972. Gov. William G. Milliken signed a bill that had rapidly sped through the legislature with overwhelming majorities.

Reportedly the lawmakers had some smart remarks to make before they were finished. One Senator from Kalamazoo (Anthony Stamm), said It looks like stuff I put on my driveway at $40 a load. Another legislator wanted to know if Chlorastrolite was any relation to the stuff that clogs arteries.Another lawmaker explained If you think my wife is going to trade in her Diamond for a Greenstone, you have rocks in your head.

A beautiful Isle Royale Greenstone.

Chemically Chlorastrolite is Hydrous Calcium Aluminum Silicate. It commonly has a polygonal mosaic pattern sometimes referred to as an alligator pattern. It can be light or dark green, but the pattern is much showier in lighter shades. Lighter green predominates Greenstones from Isle Royale, while many Keweenaw Greenstones are darker. A desirable Greenstone trait shows radiating lines exhibiting Chatoyancy like Tiger-eye.

A solid Greenstone has a hardness of 5.5 to 6.

Tumbled Greenstones ready for sorting. Most of these are good for jewelry.

Chlorastrolite is formed in vesicles (small holes in bubbly Botryoidal lava) in the upper strata of the lava flows. In many cases in the Keweenaw, the vesicles do not completely fill, and you get hollow nodules. Imagine cutting a large Greenstone, thinking how big and splendid and special it is, plus how much money it might be worth, and all of a sudden, you bust through to a hollow center. Everyone that cuts quantities of Greenstone has done this. It’s very frustrating indeed. I will leave out the expletives uttered when this happens.

On the other hand, sometimes a hollow core may have been later filled with another precious mineral found in this area–Thomsonite, Prehnite, Datolite, or even Copper. These elicit a WHOOP! sound from me. I have even seen hollow Greenstone with copper crystals inside. (For more on my favorite Greenstones with inclusions read The Shades and Patterns of Greenstone (Chlorastrolite) May 1, 2016

Sometimes I just take the entire Greenstone and matrix and pop the Greenstone out as needed.

A Greenstone found underwater off Isle Royale in1961 by Arthur Vierthaler is in the Smithsonian and is claimed to be the largest Greenstone ever found at one and a half inch by three inches. I have seen many larger, and have personally cut a two inch by four inch one myself.

Shall we go way back in time? In the 1890s to the 1900s Isle Royale Greenstones started to appear in New York City. Socialites assumed they were of French origin because of the name. These ladies were somewhat lacking in geographical knowledge, and although there was minor interest in stones from romantic France, when it was found they were from a remote Island in Lake Superior, interest waned. Michigan Greenstones were relegated to the curio category and only had a passing interest.

Greenstones from Isle Royale. Collected 50 years ago.

Greenstones had more recognition in the Midwest where they could be purchased at Wisconsin and Northern Michigan barbershops and saloons. Today, Greenstone dealers still do not get the customers for Greenstones that they warrant. Because Michigan Greenstones come from such a limited area of the world, few people have ever seen one. They are basically a one source gemstone and that source is the Isle Royale National Park, (where they’re illegal to remove), or in the Keweenaw Peninsula, where they’re becoming more scarce because of all the Private property and all the old dump piles having been crushed and hauled away for road fill.

Michigan Greenstones may resemble several other vesicle-filled stones that are found in these areas. These nodules can be Chlorite balls, Chlorite covered shot copper, Copper agates, Greenstones, or other things. We may find what we call Greenstone Wanna-Bes. On the outside these appear as if they may be Greenstones, but when we grind them, they become green dust or mud. They just didn’t get fully baked by the geologic forces I guess!

Over the years I have accumulated not only vast amounts of Rocks, Minerals, and Fossils, but occasionally when I purchase an old collections from an Estate or garage sale, I also see old rock books or, if I am lucky, some notes or historic data on rocks and minerals.

Years ago I visited an estate sale of a well known Geologist/rockhound and discovered a couple boxes of documents, maps, notes, articles, and books no longer in print. To me, these are just as valuable as any rocks I might find. These papers and books contained secret locations, historical data, and many, many other valuable resources. I cannot explain you how excited I was to find these boxes; even more excited then finding that bonus fry or three on the bottom of the McDonalds bag.

I started to dig through these boxes and other archival resources and see what tidbits I could find on Chlorastrolite (AKA Greenstone). I know I have written about Michigans State Gemstone many times, but I am always looking to find something new from the old articles. Much of the information in this blog is from my treasure trove of old resources.

The Chlorastrolite Now Michigans Official Gem by E.W. Courter Lapidary Journal November 1974

Footnote on Chlorastrolites by Lee Carter Lapidary Journal October 1969

Other information delved from papers of the late Don H. Clarke

At Snob Appeal Jewelry we sell high-quality, hand-crafted, wire-wrapped stone jewelry specializing in stones from the Great Lakes Area. You can see our Michigan Greenstone cabochons and jewelry, Lake Superior Agate jewelry and other Keweenaw stones, Petoskey Stone jewelry,and stone and agate jewelry from around the world.

Datolite Jewelry from Keweenaw Datolite

Caledonia Gem Red

We offer a wide selection of gemstone jewelry from Great Lakes stones, but a favorite gem of ours may be one you have never heard of. We are pleased to offer a great selection of Datolite Pendants, because it is so unique, colorful, coppery, and generally surprising. Datolite is not one of those “pretty sounding” jewelry names like Larimar or Sleeping Beauty Turquoise, but it is indeed very beautiful and exceedingly rare, particularly in bright, pastel colors that some of the mines were famous for. Datolite is a Michigan gemstone that should be better known.

Franklin

Mesnard

Quincy

Clark Mine

The old Copper Mines of Michigan’s historic Copper Country have produced colorful Datolite of which there is no comparison. We are fortunate to have hunted Datolite, and bought old collections over the last 30 years, always looking for great colors. Finding coveted, colorful Datolite today is rare because of several factors.

Caledonia

Closeup showing massive copper content. This Datolite virtually shines in the sun from the copper content.

HUNTING DATOLITE TODAY

Over the past 5 years many of the old copper spoil piles have sadly been crushed and used as road fill, both under paved roads and to stabilize forest roads for logging operations. Most of the few old mine dump piles left are privately owed and unfortunately, but understandably, in this lawsuit-happy world, the owners are hesitant to permit rock picking on their piles. Unstable rock piles can be quite hazardous and we hear of injuries every year caused by many factors. Frivolous lawsuits can totally dissuade what used to be rockhound-friendly mine owners from allowing anyone on their piles.

Copper, Calcite, and Datolite from the Central Mine.

Deleware

Gorgeous Mesnard

I have always felt that if I am collecting rocks it’s my owe damn fault if I injure myself. i always have my mind trained to automatically think “If i do this, then this might happen”, especially while climbing around on, or moving rocks. Money hungry specimen miners have even tunneled into rock spoil piles in the winter for valuable, colorful Datolite in years past.

MINERAL INFORMATION

Like most of the minerals and metals in the Keweenaw Copper Country, Datolite was formed in the amygdaloidal basalt through hydrothermal precipitation. It is associated with prehnite, epidote, native copper, calcite and a variety of zeolites. You could also say it is associated with chlorastrolite as it may be included in the greenstone, as can zeolites.

The Mohs hardness of Datolite is stated to be 5.5, but from my cutting experience, the hardness can vary even within a nodule or Datolite piece. Other minerals mixed in with Datolite can also be of different hardnesses, which makes cutting and polishing a copper-included Datolite quite challenging. A Datolite from the Keweenaw Peninsula can either form in seams or as nodules with a texture of cauliflower, with no hint of what is within. The most Datolites are white and have been found in all the Datolite collecting areas. Savvy Datolite hunters look for Nodules that have a light colored, cauliflower-looking skin and often porcelain-looking shards of white on the piles. Often what is found may indeed be some old dinnerware, but other times it is Datolite. Datolite is a Calciumborosilicate and it’s not unusual that it may resemble glass or porcelain. Some high temperature, high strength glass, such as Pyrex, is a BoroSillicate. One of the most glass-like, solid Datolite, from my experience, was found at the Isle Royale Mine #7 near the now Walmart location in Houghton. The Datolite from the Isle Royale Mine #7 has been made into very stable beads in the past, harder and higher in Silica than most other area mines. It is normally a translucent very pale white-green, but very nice blue Datolite has been found at the Isle Royale.

Quincy

Isle Royale Mine pendant and beads.

Isle Royale Mine Blue

DATOLITE COLORS

Experienced Datolite hunters are able to make educated guesses as to what mine a Datolite came from, based on color and crust. Keweenaw Datolite has long been treasured for jewelry and offers a broad spectrum of the rainbow. The Canary yellow from Keweenaw Point, the blue/greens from Centennial, and apple reds from various mines, and bright orange/yellows from the Quincy/Franklin/Mesnard mines are some of the most coveted. A great source of pictures to identify Datolite colors from different mines is Jeff Anderson’s Dwarves Treasures page. His favorite mineral is Datolite and he has sample Datolites from many locations.

My metaphysical friends tell me that Datolite can sharpen all mental abilities. I’m afraid that even though I have worked with Datolite for many years I still forget things. I tell people I’m in my “Wonder Years”; just today I wondered what day it was, where my TV tuner was, where my car was parked, and where Bonnie (wife) went to.

Even though I’ve owed this spectacular 38 Gram piece of luscious canary yellow Keweenaw Point Datolite for some time, you’ve never seen it. I have not decided what I’m going to do with it yet. High Grade Yellow Point Datolite is the most rare of Keweenaw Datolites, therefore the most valuable Datolite there is. I did not enhance this Datolite; This is exactly what it looks like.

The prices of Datolite Jewelry can vary widely based on scarcity, color, size, and quality. Remember that because of the vanishing mine dump piles, Datolite hunting is now very limited. Many prime locations of the past are long gone, buried, flooded, or ground up. These factors combine to make Datolite jewelry pieces great heirloom treasures which can be passed down through your family with their story. Many times someone will be seeking a Datolite from a certain mine because a relative had worked there many years ago. Quincy or Delaware Datolites are popular because people want to remember their tour of those mines.

Datolite pendants are very popular at Copper World, our retail outlet in Calumet. You may be able to purchase a rough Datolite there also.

Really good Datolite (jewelry) is a great investment, and like Western Turquoise, many the sources are no longer available. Any jewelry from Michigan’s Copper District is a good investment with a historic backstory, but for color and variety you can’t beat Datolite Jewelry.

Why is Don so busy?

The first day of the month came and went and I failed to post a new blog! I apologize for my tardiness, but it’s been unbelievably busy around the shop.

One of my projects was this new Secret Gem-Extracting Set-up, shared with you here for the very first time. Many Michigan Greenstone matrix rocks were hammered here in the last month. Some other folks even tested this slick set-up.

This is my Redneck Gem Extracting Device. Comprised of an old, bent Cadillac Wheel, a Granite Table Top, a Cheap Chair, a leveling “system” for the chair, and some broken patio blocks so the cheap chair doesn’t sink into the porous ground.

A Greenstone-Infested Rock to break.

Here’s one I got!

Another project involves getting ready for our move to the Southwest for the winter–getting lapidary equipment and stones aboard the RV. Bonnie says I have to “limit” what I take to make jewelry from, but it’s hard to chose. The new bead drilling machine requires tumble polished rocks to drill, and I loaded up 50# of beautiful Lake Superior Agates, 25# of Isle Royale Greenstone (Chlorastrolite), 5# of gorgeous, old stock, polished Thomsonite pebbles, and of course, some small polished Petoskey Stones. The Petoskeys will be easy to drill, and the others all have different challenges. I’ve never used the new bead driller, so there will be a learning curve.

I have a rock tumbling system that runs three 12# barrels of stone at one time, but still it has taken me three months to get these little beauties ready for drilling.

Finished, ready to drill.

Are these Thomsonite great, or what?

Screen and rinse before polish. The secret here is to take your time and make sure ALL the grit is off the stones before they are polished.

Finished polish on these Greenstone, sort out the non-Greenstone stuff and I’m good to go.

The custom Christmas orders are appearing in the mailbox, as well as customers purchasing Greenstone cabochons for their jewelers to make jewelry for them. The very old stock Greenstones actually from Isle Royale see popular lately..Bonnie is working on posting several more shortly.

I’ve created several fine Greenstone jewelry pieces for customers, but it is my policy not to post pictures of these until after they are gifted.

This month I’ll just show you my work of the past few months in preparation for winter bead drilling. Some of the Greenstone cabs I’m showing will be on the website soon, or you can call or E-Mail, and I’ll flag the stone for you.

It’s great to keep busy, but there are days when I’m just too busy. I think right now my head is still above water, and I hope it continues. Wish me luck.

Greenstone Jewelry, Where’d you get that big one?

Compared to a normal sized Greenstone, this one is a giant!. I can hear that little one screaming “I’m not worthy, I’m not worthy”.

Unfortunately, one of my long time friends in the Keweenaw developed some medical issues and can no longer cut rocks. On a recent trip up north, I was able to purchase some Greenstones that he will no longer be able to process into gemstones. A few were sizable.

Greenstones fill vugs in the Amygdaloidal (bubbly) basalt. These bubbles were created as gasses tried to escape from the lava as it cooled. In the Keweenaw the little bubble voids (Vugs), eventually filled with Silica (that produced Agates) or other minerals like Datolite, Thomsonite, or Greenstone. Copper and Silver also filled open areas in the basalt. Most all minerals and metals percolated up as super-heated, mineral and metal rich steams. That’s the very simple explanation of the Keweenaw lava. These lava flows were some of the most massive eruptions ever on earth. Most of the lavas in the Keweenaw simply bubbled up from giant rifts in the earth.

OK, I got off track here; so I see these Greenstone nodules in my mine rock and use small extraction tools to “pop” these out (where did that one fly off to?).

I always get excited when I work a really big Greenstone nodule. I’ve also learned not to get my hopes up too high; a lot of these big potentials turn out to be hollow or have a poor pattern.

Hidden under this pendant is a Quarter. Not the largest I’ve ever cut, but not a slouch by any means.

The back was fairly dead.

I usually grind the Chlorite husk off and see what’s inside. This particular stone had potentially nice pattern on one side, but was dead (no pattern), on the other. More than an hour later a really fine, big, Greenstone was finished. It’s now jewelry.

I wrapped that 9 gram Greenstone unisex style so anyone can wear it. At about 1″ across in all directions, it’s a fine piece. There is actually a Quarter under it, to give you an idea. I’ve cut many bigger ones, but these big ones are getting very scarce now days, as the old spoil piles are being crushed and hauled off for road fill.

I’ve been very busy cutting Greenstones lately, and sometimes I get a bit of a surprise. I thought you might appreciate a few oddballs and a couple very nice Greenstone.

A great Greenstone all the way around.

“Holy Greenstone Batman, it’s a Ninja Turtle”. Zeolite lining in depression.

Awesome! Greenstone in Patricianite.

Greenstone in Calcite

The reverse is all Calcite

There’s something unusual about the reverse.

The back side is Quartz. You can see the Chlorastrolite through the Quartz.

Nothing special, just a nice little Greenstone.

These other beauties are on the “to wrap” list or will be sold for other’s to work with. These are all from different locales and different hunts. Be sure to visit our Greenstone Pendants page and our Greenstone cabochon page to see current offerings.

It’s always a thrill when a plan comes together; and it did with this stone.

A Perfect Petoskey Stone Fossil

The entire specimen about 3″X6″

Notice the Detail?

Do you really know what a Hexagonaria Coral looked like when it was alive during the Devonian Age? Neither do I. You can get an idea by looking online at artist’s rendering based on what corals look like today.

The Petoskey Stones we find in our area of NW Lower Michigan are lovely; whites, grays of various shades, and sometimes a little pink, yellow, or blue mixed in. These are calcified fossils and polish to an attractive shine that enhances the coloration and pattern.

Underside

Many years ago I purchased a collection of rocks and minerals that contained one very remarkable Hexagonaria. I just put it aside and forgot I had it for about 20 years. My wife Bonnie sometimes dares to comes down to the shop and TRIES to as she says “neaten up”. She rediscovered this fossil with others back in the recesses of my storage area.

Hexagon shaped chambers with polyps’ peaking out

Close-up of Polyps. Notice the chamber wall striations.

I was amazed at the detail of the fossil. I simply cleaned the dust and cobwebs off with some Dawn soap and a toothbrush. I ground off the rough bottom so it sets straight. Imagine my surprise when my hard diamond wheels were sparking and I found that the fossil was not the normal Calcite, but very hard Quartz. Because this Petoskey was a Silica replacement fossil it remained undamaged and perfectly petrified for these millions of years. I have to suspect that this fossil was early Devonian. I have no idea where this specimen was found, but I was happy it was re-found in my barn and I could show it to you.

First off, my fossil has a yellow tinge. All the individual Polyps show high resolution and even perfect mouths. The living part of the Hexagonaria was called a polyp, and the dark spot we see in the center of the Hexagon shaped chamber was the polyp’s mouth. The animal had tenticles like most modern corals, that grabbed plankton as it drifted by then fed this food into its’ mouth.

See the tentacles?

The resolution is so good in this fossil that you can actually see some tenticles and perfect striations on the walls of the individual chambers.

I am knowledgeable about Petoskey Stones, but I am by far not a leading expert. I base my text on what I know from collecting devonian Fossils for 40 years.

Jewelry Making Just Got A Lot Easier

The Diamond Pacific Titan is big and bold. The Pixie (on top) that I take in my RV is a dwarf compared to its “daddy.”

People who have seen my shop will agree that it is pretty well equipped. I was able to cut and polish about any rock, but two things I was not able to do was cut and polish big Petoskey Stone.. I’ve solved this issue with a new machine I found in Tucson.

I own three cabochon machines; the Popular, six wheeled, Diamond Pacific Genie, a seven wheeled Diamond Pacific X-pert, and a Pixie. These machines have limits as to how big a stone you can polish. It has always been difficult to polish that large Petoskey Stone due to the wheels on these machines being close together. The six inch wheels on these machines have their limitations also (the pixie has 4″ wheels).

My dream machine has always been Diamond Pacific’s monster machine, the Titan. It has 8″ wheels, a 3/4 HP motor (Compaired to 6″ wheels and 1/4 HP for the aforementioned machines). Those large Petoskey Stones are no longer out of reach with my Titan. The story of the Titan’s acquisition is interesting.

With credit card in pocket, on the first day of the Tucson Gem Shows, we headed out to the Kino Sports Complex, where Diamond Pacific has their display and sales. But first, we decided to stop in and have a look at the 22nd Street Show.

While having a preliminary look around the show, Bonnie and I separate. Different things interest her than me, so the usual procedure is to set a back and forth pattern so we have some idea where each other may be. The 22nd street show tent is about 1/8 mile from end to end, so things can be missed. Bonnie caught up to me near the end of my 1/2 mile walk (back and forth four times). She ask if I saw the display that a couple had that were going out of the rock business. She said they had some rocks they were clearing out. ROCKS? I’m there.

Upon arrival at this booth I missed, I noticed many 8″ grinding wheels. What takes 8″ wheels? Correct, the Titan. I also noticed a small sign for a used Titan for sale. The elderly gentleman was a Diamind Pacific Dealer, and due to health reasons, was getting out of the rock business. It didn’t take me long to strike a deal after looking at his machine out in his SUV. Since these machines are almost indestructible, a used one is usually as good as a new one, except new wheels are sometimes needed. Since he had new grinding wheels, I bought a new set.

The Titan is a monster 16″ wide, 42″ long, weighing in excess of 130#. We had to come back the next day and pick it up, after clearing the back of our Tracker. The machine fit in the tracker with less than an inch on either side. Fortunately our daughter lives in Tucson and kindly loaned us a space in the garage for storage. Happy me! The Titan rode back to Michigan in the back of the towed Tracker.

Let’s see how long it takes to polish up this Petoskey.

I haven’t had this too long, but thus far it’s been great.

It’s coming!

The soft wheels really get the scratches out.

Now to the polish.

The lights in the shop really make the colors odd, but in the studio lighting the true colors and patterns appear.

The Titan, as mentioned, is capable of polishing those larger Petoskey Stones. I set the machine up and tested its mettle by polishing a 4″ X 5″ Petoskey stone. I show you the grinding procedure that took about a third of the time as the Genie; really amazing.

First cabs cut on the Titan

I also took some Lakers from rough to cabochons to test the Titan on smaller projects. I thought “why did I wait so long to get one of these?” Everything is so much easier and faster with better results. Now the possibilities have expanded. I eagerly look forward to going to “work” each day.

Yellow Datolite from the Delaware Mine (and Other Places)

Classic Delaware Yellow. The color is corrected in this picture to reflect the true color.

What I bought in Tucson-Part 3

Sometimes I find unusual things in odd places. Bonnie was perusing my friend Gary Wilson’s booth at one of the major Tucson Shows, when she spotted three slices of Yellow Datolite. All were from the same piece of Datolite. Yellow is one of the most sought after colors in Datolite.

Most Keweenaw Datolite sports a wide range of coloration caused from small copper inclusions ranging from orange to red to pink. White is the most common color and was found in all the Keweenaw mines. Yellow Datolite is rarer, getting it’s color from manganese, which is not as abundant as copper. The finest bright yellow is found around the tip of the Keweenaw Peninsula, the northernmost land in Michigan. Fine yellow Datolite has been found at the Quincy, Franklin, and Mesnard mines. Often these three mines had mixtures of colors that looked like they were stirred together, and not quite mixed enough. These three mines as well as the Centennial (blue) are historically the gourmet Datolite collectors Favorites.

Yellows are also found in other mines including the Delaware and Connecticut. Often, Datolite colors can be fairly specific to one mine, and yellow shades are ones you can often determine the source from the hue of the stone, but we Datolite collectors can sometimes be fooled by yellows.

The Delaware Datolite cut into three pieces. I have a couple more to wrap.

The king of yellow Datolite; The ultra rare Kewenaw Point.

The Quincy Mine produced a wonderful caramel yeollow. This little beauty I made for this blog.

The Delaware mine tailings pile has all been hauled away and that historic site for hunting Datolite is now extinct. Enjoy these Datolites while they are still available.

Prehnite and Other Pebbles from the Keweenaw

I discovered quite a few samples of Prehnite mixes that I found in the Keweenaw. All of these came from my cabochon collection, so I decided, this month, to follow up my blog on Patricianite in October, by showing you a small sample of what can be found on the beaches and in the hills of the Michigan’s Keweenaw Peninsula. Out of all the rocks and minerals in the Keweenaw, these little Prehnites are one of the most common treasures. On the beaches they wash in as pastel pebbles standing out against a rocky background of reds and browns. In the forest roads, quite often, Prehite’s have a white crust ( a little secret Rockhounding tip) with no clue as to what is hidden under the crust. I just pick them, take them home, and grind off a bit of crust. Maybe there’s treasure under the crust, maybe not.

I do not own expensive scientific instruments like a Scanning Electron Microscope (SEM), so I do not have the capability of analyzing every Prehnite mix I find, but I can tell you there is no limit to Nature’s recipes in regard to these beautiful pastel Treasures.

You may know that in the past, because of their resemblance to the Zeolite Thomsonite, this variegated, sometimes eyed Prehnites, were thought to be Thomsonite. Research done at Michigan Tech revealed that these “U.P. Thomsonites” were substantially Prehnite Mixtures. The old time rockhounds still refer to these as U.P. Thomsonite.

Sometimes you feel like an eye, sometimes you don’t. I suspect the suspect on the left may include Datolite.

Lovely pastel greens and pinks (color caused by micro-copper inclusions) dominate U.P. Thomsonite.

The patterns are so varied it's amazing.

The patterns are so varied–collecting is fun and addicting!.

Notice the brachiation (various spellings) in the right hand stone.

Jewelry grade

Can you make jewelry from Keweenaw Prehnite?

Botrioidal Keweenaw Prehnite rough

A thin Patricianite seam. Yes, that copper sheet is embedded in it.

Patricianite Rough (Non-seam material)

Here’s a little trivia you may not know about the mineral Prehnite: The first modern mineral to be named for a person was…..PREHNITE. Abraham Gottlob Werner of the Freiberg Mining Academy, was a popular teacher, but is also credited for delaying the advance of Geology by insisting upon wrong concepts on the origin of rocks and minerals. He WAS successful in classifying minerals. Werner named the mineral Prehnite after Col. von Prehn after von Prehn brought the mineral to Europe from the Cape of Good Hope (1783), where he found it.

I love rock trivia. I found this knowledge in a 45 year old book I have. Let’s take a look at some of the variations of Keweenaw Prehnite. Where possible I will show the cabochon before it became jewelry.

This Patricianite sports loads of Copper. I think it would look good as jewelry.

Why, yes indeed it did look good as jewelry.

Prehnite is a Copper Associate Mineral in Copper Country. Much of the Prehnite contains copper dust that changes green Prehnite to pink Prehnite. Other inclusions in Prehnite also produce a plethora of colors. Zeolites sometimes mix with Prehnite (A calcium Aluminum Silicate) in the Keweenaw and produce feathery eyes and patterns. Copper and Chlorite included Prehnite is sometimes referred to as “Patricianite” by copper country locals.

Pastel Patricianite with small Copper Inclusions. This was a massive chunk before slabbing.

Another one that made great jewelry.

Pastel Prehnites roll up on the beaches all along the west side of the Keweenaw Peninsula. While looking for agates, beachcombers may see a bright pink stone shimmering among other dull stones. Pick it up, it might be a coppery beauty. These nuggets can have pink and green together, sometimes even purple tones. I have found Prehnite in piles of materials cleared from road construction not far from Calumet. Prehnites are also gleaned from rock spoil piles at some mines. I have a secret hole that I also occasionally excavate for Prehnites. The best Prehnite has always been associated with Austraiia, but gemmy pastel green Keweenaw Prehnite with Copper inclusions, in my opinion, gives the Aussie stuff a run for the money.

Prehnite with Copper. This is the high quality stuff often found in slim seams.

Prehnite with very little Copper. This is the high quality stuff often found in slim seams.

Prehnite is sometimes referred to as U.P. Thomsonite because its’ appearance often mimics Thomsonite, with eyes, radiating sprays, and variegated inclusions. Some Prehnite is difficult to tell from Thomsonite, or other Zeolites, and for many years Prehnite was thought to be a Zeolite. It was determined by Analysis by Michigan Tech geologists that Prehnite is not related to the Zeolites, but can be associated with Zeolites. Prehnite is a Calcium Alumosilicate. More confusing is when Zeoiles mix with Prehnite and make the Prehnite look exactly like Thomsonite. Thomsonte is almost an exclusive American Gemstone (more trivia for you guys), Prehnite is much more scattered and can be found in numerous locales around the world.

Loads of Copper in this Prehnite. Mine seam material.

Loads of Copper runs through this Prehnite, a mine seam material.

A beautiful oddball dug from a hole somewhere in the Keweenaw Peninsula. Prehnite, assorted Zeolite and other stuff. A beautiful mix, don’t you think?

The Apple Green Prehnite from the Keweenaw can be found as small round Crystals, but in most cases as slim veins in the Amydaloidal basalt. I have found much of the Prehnite in my collection in veins that are less that one inch. The Prehnite seems to form within a void from the outside in, meeting in the middle of the void. After extracting the Prenite bearing host basalt, I usually split the Prehnite where it meets in the middle. I can then use both sides to make beautify cabochons and jewelry. I like when the Prehnite sometimes does not completely close off in the middle of the seam, leaving a void where Prehnite Crystals form in a drusy. Remember it is often possible to find copper within the U.P. Prehnite. Copper can be found included in most every Keweenaw mineral.

The Seaman Mineral Museum, in Houghton, Michigan, has some wonderful, large Prehnite crystals found by miners over the years. Knowing that a Mine Captain or Superintendant or other mine management person was a mineral collector, the miners could score some points by turning these specimens over to them. Some of the finest specimens at the Seaman Museum were from these historic collections donated to the museum by heirs or willed by the owners of the collections.. Two of the most prolific collectors were J.T. Reeder, who clerked at several different mines, and L.L. Hubbard who discovered the Champion Mine and served as general manager of the mine. It is interesting to read and learn about these early collectors. Hubbard willed some of his collection to the University of Michigan, and recently the U of M has given many Copper Country specimens, from historic collections, to the Seaman Museum.

Many rockhounds overlook Prehnite or Patricianite while rock collecting in the Keweenaw. it’s one of my favorites and I never miss a chance to pick up nice pieces. So what do you think? Does Prehnite/Patricianite make good jewelry? You are invited to visit my jewelry pages to see the variety created from Keweenaw Treasures, especially Prehnite .