ziggy
spending too much on rocks
Member since June 2016
Posts: 483
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Post by ziggy on Aug 9, 2017 18:37:05 GMT -5
Hubby finally polished up a couple of greenstones we broke out of some amygdaloid basalt. They are pretty dark ones and not real chatoyant unfortunately. So far only about 1in 10 stones actually have any greenstone patterning. Photo below under florescent light. Below is the same stone next to a penny and shot with a phone call flash. There is a touch of datolite at the top. That stone needs the edges straightened and will most likely find a home in a ring someday. The smaller stone pictured below is the second out of about twenty stones to actually have turtleshell pattern. A closer view We are already running out of large (meaning the two shown, which are actually pretty large for greenstones) stones to polish but we have a mess of medium sized ones.
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Post by rockjunquie on Aug 9, 2017 19:46:45 GMT -5
Thanks for posting these. I hadn't seen them before, but now that I have seen them- I think I had one and gave it away before I knew much about rocks. It was about as big as these. I had no idea what they were.
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ziggy
spending too much on rocks
Member since June 2016
Posts: 483
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Post by ziggy on Aug 10, 2017 20:17:46 GMT -5
Thanks for posting these. I hadn't seen them before, but now that I have seen them- I think I had one and gave it away before I knew much about rocks. It was about as big as these. I had no idea what they were. They don't get very big and are pretty rare. The correct name for them is chlorastrolite. They are only found on Isle Royale in Lake Superior and in some of the amygdaloidal basalt poor rock piles in the Keweenaw peninsula. Isle Royale is a National park and collecting there is against the law so all new examples of this mineral now originate in the mine piles. The best ones are found on Isle Royale. What makes it good? The best ones have turtle shell pattern and good chatoyance. The mine pile ones are darker in color and never found looking like the classic water worn and polished ones from the island. Plus, on the island they are found sans matrix. The ones from the mine piles have to be busted free from the basalt matrix then manually polished. The Michigan Greenstone is the state gem of Michigan as well.
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ziggy
spending too much on rocks
Member since June 2016
Posts: 483
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Post by ziggy on Aug 10, 2017 20:32:24 GMT -5
We did find some exceptionally large greenstones. Two are pictured below. The one on the right is rough with no polishing and (don't tell anyone😉) has been epoxied back together after splitting neatly in half upon extraction from the basalt matrix. The one on the right looks like it is going to be one of the nine out of ten that isn't going to be a good looking one after some preliminary polishing shows almost no pattern.
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ziggy
spending too much on rocks
Member since June 2016
Posts: 483
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Post by ziggy on Aug 10, 2017 20:54:55 GMT -5
Below is a photo of some basalt matrix with amygdaloids filled with greenstone. Below is a photo of a HUGE greenstone still encased in a super hard piece of basalt. I don't think this one will ever come out in one piece.
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Post by spiceman on Aug 10, 2017 21:04:34 GMT -5
Greenstone, found a nice chunk months ago. Looked it up and the largest chunk of greenstone is at the place we always went fishing. Minnesota, Ely but back in the 1980's Rocks were the last thing on my mind. It was weird that I knew the location of Ely. Ely is not far from the Canadian border.
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ziggy
spending too much on rocks
Member since June 2016
Posts: 483
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Post by ziggy on Aug 10, 2017 21:21:57 GMT -5
Greenstone, found a nice chunk months ago. Looked it up and the largest chunk of greenstone is at the place we always went fishing. Minnesota, Ely but back in the 1980's Rocks were the last thing on my mind. It was weird that I knew the location of Ely. Ely is not far from the Canadian border. Uhhhm...,.spiceman......you must be speaking of something other than what I am. The greenstone I mention can not be found in Ely Minnesota. The largest known piece of (chlorastrolite) greenstone resides in the Smithsonian and is about 1 1/2 cm by 3 1/2 cm. That is pretty small. All locations for finding it as far as I know are in Michigan. Hence, it having the designation state gemstone of Michigan. Perhaps there is something in Ely known as greenstone, but it is not the mineral called chlorastrolite, which is the correct name for what is called greenstone in Michigan. You must not have read anything I wrote previously.
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Post by spiceman on Aug 10, 2017 21:54:45 GMT -5
Greenstone, found a nice chunk months ago. Looked it up and the largest chunk of greenstone is at the place we always went fishing. Minnesota, Ely but back in the 1980's Rocks were the last thing on my mind. It was weird that I knew the location of Ely. Ely is not far from the Canadian border. Uhhhm...,.spiceman......you must be speaking of something other than what I am. The greenstone I mention can not be found in Ely Minnesota. The largest known piece of (chlorastrolite) greenstone resides in the Smithsonian and is about 1 1/2 cm by 3 1/2 cm. That is pretty small. All locations for finding it as far as I know are in Michigan. Hence, it having the designation state gemstone of Michigan. Perhaps there is something in Ely known as greenstone, but it is not the mineral called chlorastrolite, which is the correct name for what is called greenstone in Michigan. You must not have read anything I wrote previously. I just googled greenstone Ely and it talks about greenstone. There must be many different types. Oh well
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timloco
has rocks in the head
Member since April 2012
Posts: 545
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Post by timloco on Aug 10, 2017 23:14:28 GMT -5
Huh that's a nice green color. Never heard of it before. Loves me some chatoyence in a rock too.
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ziggy
spending too much on rocks
Member since June 2016
Posts: 483
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Post by ziggy on Aug 11, 2017 6:54:06 GMT -5
Uhhhm...,.spiceman......you must be speaking of something other than what I am. The greenstone I mention can not be found in Ely Minnesota. The largest known piece of (chlorastrolite) greenstone resides in the Smithsonian and is about 1 1/2 cm by 3 1/2 cm. That is pretty small. All locations for finding it as far as I know are in Michigan. Hence, it having the designation state gemstone of Michigan. Perhaps there is something in Ely known as greenstone, but it is not the mineral called chlorastrolite, which is the correct name for what is called greenstone in Michigan. You must not have read anything I wrote previously. I just googled greenstone Ely and it talks about greenstone. There must be many different types. Oh well I'm sorry spiceman. I should have never referred to it by it's nickname. Perhaps you should Google chlorastrolite instead. 😉
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ziggy
spending too much on rocks
Member since June 2016
Posts: 483
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Post by ziggy on Aug 11, 2017 7:13:10 GMT -5
I just googled greenstone Ely and it talks about greenstone. There must be many different types. Oh well I'm sorry spiceman. I should have never referred to it by it's nickname. Perhaps you should Google chlorastrolite instead. 😉 It's also known as pumpyllite. I googled ely greenstone and found that the greenstone there is a form of pillow lava and is at best a distant cousin of a rock to Isle Royal greenstone. Not as expensive or worth as much as chlorastrolite, but locally (in ely at least) famous. You have led me to learn about a mineral I never heard of so thank you😁
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Post by spiceman on Aug 11, 2017 18:03:19 GMT -5
You are welcome. You have also got me to know more about green stone. Thank you too.
Oh, don't be "sorry" you did nothing wrong.:)
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ziggy
spending too much on rocks
Member since June 2016
Posts: 483
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Post by ziggy on Aug 20, 2017 11:45:15 GMT -5
The almost final tally of finished greenstone "cabs" (and I use that term loosely). Turns out the ratio of actual well patterned stones to useless ones is about 1 out of 10. So, I polished 130 stones to come out with these 13 stones. Good thing is, you can almost always tell a useless stone with only a little grinding. The big one on the left has orange datolite and the big elongated one above the one with datolite has a copper inclusion which is the light dot on it
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