Kai
spending too much on rocks
Member since December 2018
Posts: 331
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Post by Kai on Mar 17, 2019 8:36:26 GMT -5
It wasn't actually a cab, it was an ordinary rock which split in two during a tumble. Size difference wasn't perfect, but was present. So the only real difference was medium, I don't use any (yet).
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Kai
spending too much on rocks
Member since December 2018
Posts: 331
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Post by Kai on Mar 30, 2019 2:29:39 GMT -5
Strangest find...! I found a stone with very regular layers of black and grey material, but... -black is very hard and glassy, can't scratch it with a steel nail, it's shiny and almost a bit transparent, like obsidian; -grey is MUCH softer, totally matte, and reactive to acid, I'd say limestone. Now the layers are so thin and so regular, this is so unusual since one of the rocks is sedimentary and the other one volcanic... was there an ancient volcano close to a sea shore? Intriguing...
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Deleted
Deleted Member
Member since January 1970
Posts: 0
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Post by Deleted on Mar 30, 2019 11:06:41 GMT -5
Now the layers are so thin and so regular, this is so unusual since one of the rocks is sedimentary and the other one volcanic... was there an ancient volcano close to a sea shore? Intriguing... Yes, "intriguing" is exactly what it is. Obsidian would not form in such thin layers over limestone (although obsidian is found in "obsidian flows," it is extruded in thick viscous masses, rather than flowing like water or pahoehoe lava). The black layers may be flint/chert, which does form in limestone, although usually as nodules rather than layers. It may have formed in the same way as so-called Zebra rock formations.
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jasperfanatic
spending too much on rocks
Member since January 2019
Posts: 456
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Post by jasperfanatic on Mar 30, 2019 11:31:56 GMT -5
These look great, and I kind of like those rocks that turn out flat/thin, especially when they're tough enough to get through the final polish. Thanks for sharing! I looked up the Soča river, what gorgeous country! All the pictures I saw of the river were a bright blue, like the ocean around the Caribbean, is that from glacial runoff?
There are no experts just those who have accumulated more knowledge. We're all newbies in everything in life, always...when we think we're experts, we often stop learning, and what's the fun in that?
"One cannot learn what they think they already know." - Epictetus
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Wooferhound
Cave Dweller
Lortone QT66 and 3A
Member since December 2016
Posts: 1,423
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Post by Wooferhound on Mar 30, 2019 12:10:28 GMT -5
Strangest find...! I found a stone with very regular layers of black and grey material, but... -black is very hard and glassy, can't scratch it with a steel nail, it's shiny and almost a bit transparent, like obsidian; Now the layers are so thin and so regular, this is so unusual since one of the rocks is sedimentary and the other one volcanic... was there an ancient volcano close to a sea shore? Intriguing...
I find that black stuff in with the Limestone and Granite gravel parking areas here in North Alabama. Collected only the black stuff and tumbled it. Rather hard and spent a long time in Stage 1.
Folks around here called it Black Chert.
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Kai
spending too much on rocks
Member since December 2018
Posts: 331
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Post by Kai on Mar 30, 2019 16:27:45 GMT -5
Thank you @rocks2dust and Wooferhound for your comments, I think it might as well be chert. I'm afraid to tumble that piece of rock because the layers are so different in hardness, I'm pretty sure I'd destroy it. Any suggestions?
jasperfanatic, thank you for your kind words, I'm glad you like Soča. There's a lot of glacial runoff in the spring, but the main reason it's so pristine blue is mostly because it's just been flowing over pure rocks and it hasn't had opportunity to get dirty with anything yet. There's no soil or mud so far up in the mountains, just pure limestone. Water over white rocks looks bright blue or blue/green. Only when it gets a bit further down onto the plains it turns more greenish colour, when it gets stained a bit with soil.
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NevadaBill
fully equipped rock polisher
Member since January 2019
Posts: 1,332
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Post by NevadaBill on Apr 1, 2019 18:37:54 GMT -5
That is a pretty rock. I like the ones that have more than one color and are more opaque like that. I hope the two materials are similar in hardness than you are guessing and tumble real well. Please share when you are done!
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Kai
spending too much on rocks
Member since December 2018
Posts: 331
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Post by Kai on Apr 3, 2019 14:04:38 GMT -5
The two materials are really different in hardness from what I've been testing (just scratching them with a steel nail) - so as I said, I'm afraid to tumble it because I'm pretty sure I'd destroy it. I think I might just try shaping and polishing it by hand.
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Wooferhound
Cave Dweller
Lortone QT66 and 3A
Member since December 2016
Posts: 1,423
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Post by Wooferhound on Apr 5, 2019 19:40:52 GMT -5
It's OK to test it. just check it after a coupla days . . .
I have tumbled both types of material in that stone and it should make it at least a week and be fine.
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Kai
spending too much on rocks
Member since December 2018
Posts: 331
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Post by Kai on Apr 8, 2019 14:47:28 GMT -5
I have collected enough rough for another batch, so I will put it all into stage 1 one of these days. Fingers crossed!
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NevadaBill
fully equipped rock polisher
Member since January 2019
Posts: 1,332
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Post by NevadaBill on Apr 8, 2019 18:57:42 GMT -5
Good luck Kai.
I don't want to derail this thread, but I am new to this, and also have been experimenting with stones that are a mix of harder and softer lately. And what I am finding is kind of counter intuitive.
When I run the rocks in a rough grit (46/70), with other hard stones (7's), and ceramic media (hard), I am not seeing a lot of undercutting after 7 or even 14 days. I see major reduction going on. But not the undercutting I was expecting.
On the other hand, when I put the rocks through later stages, some undercutting begins to be obvious? Well, so far. Plus I am learning that there is a special technique needed to get the soft half to polish. The hard 1/2 wants to though. hehe.
Keep us posted!
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Kai
spending too much on rocks
Member since December 2018
Posts: 331
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Post by Kai on Apr 9, 2019 13:41:10 GMT -5
That's strange, but certainly interesting! Thanks for your input. Well, only one day so far, so I won't be opening the drum anytime soon yet. Still lots of finger-crossing to be done!
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Post by Rockindad on Apr 9, 2019 16:35:24 GMT -5
Good luck Kai. I don't want to derail this thread, but I am new to this, and also have been experimenting with stones that are a mix of harder and softer lately. And what I am finding is kind of counter intuitive. When I run the rocks in a rough grit (46/70), with other hard stones (7's), and ceramic media (hard), I am not seeing a lot of undercutting after 7 or even 14 days. I see major reduction going on. But not the undercutting I was expecting. On the other hand, when I put the rocks through later stages, some undercutting begins to be obvious? Well, so far. Plus I am learning that there is a special technique needed to get the soft half to polish. The hard 1/2 wants to though. hehe. Keep us posted! It makes sense if you think about it. During your 46/70 stage (or 60/90 and perhaps even 120/220) all of the materials in a given stone are being ground down indiscriminately, perhaps not at the same exact rate but close enough. As you move to finer grits the focus is more on scratch removal which is fine for the harder materials but it is still coarse enough to remove the softer material. I read a post fairly recently (cannot find it now- I think by Tommy ) about this same phenomena in cabbing. The difference is in cabbing you have the luxury of being able to see it happen in front of you and can figure out at what grit this is happening and spend less/no time there. Not as easy in tumbling. As my boy seems to favor every soft and mixed hardness rock out there we are dealing with this constantly. While I love a good challenge it is no mystery why a lot of people stick to jaspers and agates. Good Luck! Al Found the post mentioned above: Tommy Administrator ***** Tommy Avatar so many rocks...so little time Member since January 2013 Posts: 7,218 Location: Pleasant Hill, CA Slice of Apple Pie badge Some recents & questions for the pros (long & pic heavy) Mar 25, 2019 at 11:47am rockjunquie, rocks2dust, and 4 more like this Quote like Post Options Post by Tommy on Mar 25, 2019 at 11:47am Another quick note about the plume and moss agates undercutting - yes the plumes will almost always reach the surface and show some 'texture' where they do. Some materials are more prone to actual undercutting than others. I don't really have a cure for it but I do try to employ a little technique where I try to spend as little time on the grit wheels where the undercutting is occurring. Ie: we know that on the grinding wheel while shaping, the wheel is removing agate and plumes at the same rate. We also know that on the higher polishing grits (3000+?) the wheel is not removing agate or plumes anymore. This obviously means that somewhere in between those two points is a grit number where agate has stopped being removed but the softer plumes are still being removed. What I try to do is as I said above - not spend a huge amount of time on the grit where undercutting is the worst - where the wheel has stopped removing agate but is still removing plumes or moss at the surface. Doing this often means that I will make a quicker jump than I would normally like to make - maybe from 280 up to 1200 or 3000 but the result will be that a lot more time has to be spent on the higher grit (often going back and forth between low and high grit) until every scratch is gone. Hope this helps a little bit. Gorgeous work you are doing. Read more: forum.rocktumblinghobby.com/user/4974/recent#ixzz5kdY2ghcc
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Kai
spending too much on rocks
Member since December 2018
Posts: 331
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Post by Kai on Apr 11, 2019 13:55:48 GMT -5
Thanks for your input and thanks that you went through all the archive and found that post for me!
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Post by 1dave on Apr 11, 2019 18:44:42 GMT -5
Well, it should better say Kai's Newbie Korner, but oh well... pssst. Anyway, lately I've been playing a lot with different gravel stones and rock-minerals that I can find when Soča river torrent brings them to the plains. Unfortunately this means that my chances of correctly identifying the type of rock are close to 0, but oh well. They look pretty, right? Good enough for a stupid newbie like me. www.gutenberg.org/files/7409/7409-h/7409-h.htm
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Kai
spending too much on rocks
Member since December 2018
Posts: 331
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Post by Kai on Apr 18, 2019 13:33:43 GMT -5
Hello from your European Newbie! Did you miss me? I thought I'd share with you two latest pretty finds of mine. They're just banded flat stones which I manually polished to dull shine. I'm considering polishing them a little bit more and then maybe just leaving them like this - rough edges, natural looking and making them into brooches or pendants. What do you think? Should I instead polish them to full shine?
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Post by 1dave on Apr 18, 2019 14:00:37 GMT -5
Nice - AND fun for you!
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Post by fernwood on Apr 19, 2019 4:31:08 GMT -5
I like those two.
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Post by hummingbirdstones on Apr 19, 2019 9:20:40 GMT -5
2 kool rocks from Kai! I really like them. Whether you want to polish them more or not is totally up to you. They look good how they are now and they'd probably look good shinier, too.
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Kai
spending too much on rocks
Member since December 2018
Posts: 331
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Post by Kai on Apr 19, 2019 14:09:40 GMT -5
Thanks, hummingbirdstones - I know it's up to me, but I like hearing your opinions, ya know? They're kinda specific and I'm not sure what to make out of them, so crazy ideas are welcome!
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