ziggy
spending too much on rocks
Member since June 2016
Posts: 483
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Post by ziggy on Dec 18, 2016 22:03:51 GMT -5
I picked up this basalt beach rock with what looked like tiny greenstone inclusions in it at Hunter's Point park just west of Copper Harbor. Hubby decided to see how big the rest of one of the inclusions was. He started carving the stone out with diamond tool bits. It is obvious he is onto something It seems to get at least 4 times as big as it looked from what was showing at first. For a greenstone it is actually getting pretty big as most of them are pea size. It started out about the same size as the inclusion on the left side in the photo below (which I'm sure is the same way, along with 4 or 5 more throughout the rock.) We'll update what we end up with as soon as we're done. Elsewhere on this rock there is also this neat bubble of what looks to me like prehnite with one little tiny speck of copper inclusion on it. It's shaped like a little mini cab and hubby was thinking about freeing it from the matrix and polishing it for a ring.
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ziggy
spending too much on rocks
Member since June 2016
Posts: 483
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Post by ziggy on Dec 18, 2016 22:39:48 GMT -5
Some of the other inclusions he is planning on excavating.
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Post by Pat on Dec 18, 2016 23:33:14 GMT -5
Neat! Wonder what it all is.
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Post by toiv0 on Dec 19, 2016 6:41:04 GMT -5
Wow great find, green stones are pretty cool. Looking forward to seeing end result. Will you or your husband make your ring?
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ziggy
spending too much on rocks
Member since June 2016
Posts: 483
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Post by ziggy on Dec 19, 2016 9:48:31 GMT -5
Neat! Wonder what it all is. The light green ones are the Greenstone (Michigan's state gem is the Chlorastrolite, a variety of Pumpellyite also called Greenstone) inclusions and the dark green spots are epidote I believe (but I'm not positive about that.)
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ziggy
spending too much on rocks
Member since June 2016
Posts: 483
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Post by ziggy on Dec 19, 2016 9:49:26 GMT -5
Wow great find, green stones are pretty cool. Looking forward to seeing end result. Will you or your husband make your ring? Neither of us have made a ring yet so it looks like we will both be learning something new.
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ziggy
spending too much on rocks
Member since June 2016
Posts: 483
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Post by ziggy on Dec 19, 2016 11:42:40 GMT -5
Progress on the greenstone extraction continues. Below you can see the grooves made around the stone by the diamond bits. After he gets it down a ways he takes it to his belt sander and reduces the sides own to the level of the diamond drill cuts. It's turning out to be a fairly nice sized greenstone, at least as far as greenstones go. The one to the lower right of the one he is digging out has increased in size also and hubby is considering ways to grind around it in the hopes that it too will be worth excavating. After he removes the excess rock around the stone, he goes and scrapes the matrix off the stone with his pocket knife so he can accurately follow it through the matrix without grinding off any of the actual greenstone. The photo below has an inclusion circled in red that is about the same size as the one he started out on.
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ziggy
spending too much on rocks
Member since June 2016
Posts: 483
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Post by ziggy on Dec 19, 2016 14:46:58 GMT -5
Hubby was picking away some matrix from the edge of the nodule and it just popped off and fell on the floor. At first we thought he broke the greenstone, but after looking more closely we realized that the stone had cleanly parted ways from the matrix. It has a funny little hook on one end/side and you can see where it fit in on the matrix in the photo below and is nearly round. After weighing the stone it came up to 1.6 grams which equates to 8 carats. The average size of a typical Keweenaw greenstone is 1 carat. Some greenstones in the mine piles can reach 3 to 5 hundred carats but these are few and far between. The price for a one gram greenstone is $116 (in the rough) and polished ones go for between $50 and $200 per carat. Hubby will be polishing this one up as he has the skills to do that stuff and I probably don't. Unfortunately, unless spring comes three months early this year, it'll have to wait to be polished. Now, on to the next nodule in this rock.
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Deleted
Deleted Member
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Post by Deleted on Dec 19, 2016 18:47:59 GMT -5
Super cool!
Glad you were brave enough to make another thread. 😎
I have never heard of that stone before. Thanks for new knowledge!!
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Post by toiv0 on Dec 19, 2016 18:57:13 GMT -5
Super glad the aw crap moment turned out ok. I wish I was so lucky sometimes extracting thomsonite. My new idea is to use a diamond hole saw.
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ziggy
spending too much on rocks
Member since June 2016
Posts: 483
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Post by ziggy on Dec 19, 2016 20:07:24 GMT -5
Super glad the aw crap moment turned out ok. I wish I was so lucky sometimes extracting thomsonite. My new idea is to use a diamond hole saw. Yeah, the aw crap moment turned into an ah ha moment. He wasn't so lucky on the next nodule he tried. He got too close with the bit and it fractured and a big chunk of it fell off before it ever got anywhere near as far as his first one. Oh well, there's three more like it still untouched. Do you get your thomsonite in Minnesota? I'm always looking for the U.P. version of it (pink prehnite) but have not been so fortunate with that search. I think when I was up there by Copper Harbor I saw a beach rock with a really tiny pink spot on it but passed it up because it looked so small. Probably should have kept it. Might be the only one I'll ever see there.
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ziggy
spending too much on rocks
Member since June 2016
Posts: 483
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Post by ziggy on Dec 19, 2016 20:11:18 GMT -5
Super cool! Glad you were brave enough to make another thread. 😎 I have never heard of that stoner before. Thanks for new knowledge!! You are most likely referring to the "jorts" incident, eh? I figured that if I didn't include any references to denim I might be OK in this one. Time will tell. Oooops. I just said denim twice.... Below is a typical finished gem quality greenstone
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Post by toiv0 on Dec 19, 2016 20:31:08 GMT -5
Super glad the aw crap moment turned out ok. I wish I was so lucky sometimes extracting thomsonite. My new idea is to use a diamond hole saw. Yeah, the aw crap moment turned into an ah ha moment. He wasn't so lucky on the next nodule he tried. He got too close with the bit and it fractured and a big chunk of it fell off before it ever got anywhere near as far as his first one. Oh well, there's three more like it still untouched. Do you get your thomsonite in Minnesota? I'm always looking for the U.P. version of it (pink prehnite) but have not been so fortunate with that search. I think when I was up there by Copper Harbor I saw a beach rock with a really tiny pink spot on it but passed it up because it looked so small. Probably should have kept it. Might be the only one I'll ever see there. Yes from MN. I live about 3 hrs from grand marais and found a good contact I have been trading with for the thomsonite. I self collect some in the Grand Marais area mostly in gravel pits and road cuts. Trading is a lot easier, there is alot around after they built one of the tunnels on Hwy 61, all the locals hauled it away by the truck load. You just have to find someone willing to let loose of some.
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Post by toiv0 on Dec 19, 2016 20:32:55 GMT -5
ziggy I will send you a chunk of rough with some nice nodules if you would like. Just pm your address.
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ziggy
spending too much on rocks
Member since June 2016
Posts: 483
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Post by ziggy on Dec 19, 2016 21:01:14 GMT -5
ziggy I will send you a chunk of rough with some nice nodules if you would like. Just pm your address. Wow! Nice offer but I will pass on it. With me it's just the thrill of the hunt. I love going for long road trips and rocks are the perfect reason to take one. The trip is as good as the destination usually for me. I thought you were up that way in Minnesota. I went through there on the way to Thunder Bay once about twenty years ago. Beautiful up there. Got some nice amethyst up there in Thunder Bay. The hole saw idea has passed my mind a couple of times when I see bedrock with stuff like greenstone and prehnite at the beaches up in the U.P. Not so sure I would ever do that at a park though. When we go back to Hunter's point next summer we are taking a rock pick with us at least because I saw this one boulder that looks a little bit too big and someone might hurt themselves when tripping over it.....
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Deleted
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Post by Deleted on Dec 19, 2016 23:17:46 GMT -5
Shhhh..........
Never mention the 'd' word again....
;-)
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ziggy
spending too much on rocks
Member since June 2016
Posts: 483
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Post by ziggy on Dec 22, 2016 14:30:55 GMT -5
Finally got all the chlorastrolite nodules out of the basalt (and one Prehnite nodule too.) Looks like eight are actually big enough to polish up. We also got at least twenty really small ones (he'll have to glue them on a finishing nail to polish them they're so small.) The one in the middle nearest the quarter is the first one he got out by careful excavation. For the rest he just smashed the basalt off of them with a rock pick. The flat sides on the two small ones near the bottom were from the edge of the rock and were the exposed side. The big one just under the quarter to the right would have been bigger but that one got cut by the trim saw (hence the flat side on that piece and the one in the middle bottom which is the cut off from it.) Now all we gotta do is hope they look good after polishing. The rock pick bashing process sped things up a lot but there were lots of cracked smaller stones that went to waste. They broke easier than the keepers though so maybe they were junk anyway.
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Deleted
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Post by Deleted on Dec 22, 2016 16:32:31 GMT -5
A tiny bit of geology research Google style shows us that this material is quite similar chemically (and visually as well) to Larimar. Your gem picture made that quite clear.
Chlorastrolite and Pectolite of similar origin and chemistry. Not identical, but very close.
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Post by toiv0 on Dec 22, 2016 16:36:10 GMT -5
A tiny bit of geology research Google style shows us that this material is quite similar chemically (and visually as well) to Larimar. Your gem picture made that quite clear. Chlorastrolite and Pectolite of similar origin and chemistry. Not identical, but very close. After you said so you can see the similarity, learn something here all the time.
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ziggy
spending too much on rocks
Member since June 2016
Posts: 483
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Post by ziggy on Dec 22, 2016 18:49:43 GMT -5
A tiny bit of geology research Google style shows us that this material is quite similar chemically (and visually as well) to Larimar. Your gem picture made that quite clear. Chlorastrolite and Pectolite of similar origin and chemistry. Not identical, but very close. The mindat page Does not show these two as being related chemically but the two minerals do look a lot alike and both do have similar crystal structure at times. Under "Relationship of Pectolite to Other Minerals" in both Pectolite and "Relationship of Pumpellyite (Mg) to Other Species" pumpellyite there is no correlation. I am not able to equate the two as they form in different environments and conditions. The Pumpellyite forms in amygdules in basalt and occurs as amygdaloid structures and fracture fillings in basalt. Pectolite forms in nepheline syenites which is a holocrystalline plutonic rock that consists largely of nepheline and alkali feldspar. The crystallography is different for the two minerals as well with chlorastrolite having Crystal System Orthorhombic and Habit Fibrous aggregates, and Pectolite has a Crystal System Triclinic and Habit Globular masses, the rarer crystals showing tabular habit. The habit of pectolite is especially liable to alteration, and in nature it is frequently altered to zeolites (especially natrolite), sodalite, kaolin, or compact muscovite. Another Zeolite that IS found in basalt in Michigan is Thomsonite (very similar to Chlorastrolite) and perhaps that might mean something although there is no info about one altering into the other. I think the Larimar looks sexier though.
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