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Post by snowmom on May 15, 2014 19:28:43 GMT -5
I read a thread last night about tumbling granite, showed some of the pieces he was not happy with because of chips or dings, undercuts... but to me they were all beautiful just the same. and went looking for more posts. I have seen some of ManofGlass's granite I know it is hard to do granite, but I want to have hope... I just love the wild colors of so many granites I find here... so show me your granite and tell me what I need to know about it, please?
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Post by 150FromFundy on May 15, 2014 19:51:32 GMT -5
Granite is basically a mix of quartz, feldspar and a dark ferromagnesian like hornblende, or biotite. Quartz has a hardness of 7. Feldspar has hardness of 6. Quartz and feldspar are close enough in hardness that they can be tumbled together with some care (lots of pellets). The problem is those pesky ferromagnesians (the black or sparkly glittery stuff). The ferromagnesians tend to be soft and/or tend to be brittle. They will erode away faster than the quartz and feldspar causing chipping and undercutting.
Your best luck for tumbling granite is to find pieces that have less ferromagnesians in them. As you know, granite varies considerably, so some pieces (or locations) have much more ferromagnesians in them, than others.
I share your love (fascination) for granite. As common as it is, it varies considerably from place to place. I'll post some photos when I dig some out. Too many take granite for granted.
Darryl.
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,159
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Post by jamesp on May 15, 2014 19:57:25 GMT -5
Granite is a great material. some of those from the Greatlakeman are real nice.
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Post by Jugglerguy on May 15, 2014 21:42:06 GMT -5
I'm a recovering granite collector. I'm trying really hard to stop. It's just so colorful! My first batch was granite. It came out pretty good, but granite never comes out perfect.
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,159
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Post by jamesp on May 15, 2014 21:45:42 GMT -5
The king of the granite greatlakeman
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Post by mohs on May 15, 2014 22:01:06 GMT -5
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Post by snowmom on May 16, 2014 4:22:03 GMT -5
150fromfundy, you don't know how badly I wanted to put that pun in the title of this thread. I was going to do it in a comment if you hadn't. Glad we got that covered (and I LOL) Jugglerguy if that is the sickness I'm not sure I'm goin' for the cure! MrMohs, I think you must have one of the busiest minds on this board... <3 (that's a heart) I am really enjoying these forums, thanks to folks like all of you.
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Post by Drummond Island Rocks on May 16, 2014 6:01:41 GMT -5
Its hard to not pick up the granite when its on the beach all colorful and shiny but the undercutting can be a pain when tumbling. these are all Lake Huron rocks with a few granites in there and here's some Michigan gowganda tillite with big pieces of granite in them Chuck
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Post by snowmom on May 16, 2014 11:31:30 GMT -5
DrummondIslandRocks, you prove my point! Who could resist those pretties? Never mind a chip or ding or undercut here and there, this is a feast for the eyes. I would not be able to resist touching them, either.
Now, question open to everybody again... is there any tumbling method (rotary, vibe, pre shaping technique, steps with certain grit or polishing) that you would use with granites especially? I would guess that one would have to be very selective and not choose stones with visible faults or cracks in them to start with? Is there a certain size that proves to have better results?
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Post by mohs on May 16, 2014 11:36:30 GMT -5
<3that's a busy heart
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Post by rockpickerforever on May 16, 2014 12:09:14 GMT -5
This is graphic granite, common in pegmatite areas.
This also material also undercuts very easily (the quartz is much harder!), you really have to be careful. I think it was easier to cab on a flat lap than it would have been on a Genie or other type of set up.
I know I've got some nice red stuff, will have to hunt it up and get some pics.
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Post by Jugglerguy on May 16, 2014 12:39:15 GMT -5
I do granite the same as any other rock. I always do the first stage in a rotary and then do the rest in a vibe.
I have a question for everyone though. For rock that undercuts easily, I don't usually notice a problem until the later stages. Everything looks good after 60/90 and 220. Its after they've been in 500 for a while that things start to go bad. Is it better to do rocks like this for a shorter time in those longer stages? I usually go 2-3 days in 500 and then another 2-3 days in 1000, then 2-3 days in polish. I think for rocks like granite, it might be better to go for only one day in each of those stages. What do you think?
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,159
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Post by jamesp on May 16, 2014 13:56:24 GMT -5
Worth a try. The finishing steps can happen very quickly. it is after all a surface alteration and not deep grinding.
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Post by snowmom on May 16, 2014 15:16:01 GMT -5
graphic granite- it does look like some sort of ancient script... I had not seen that before... very neat! I have no idea how it would be best to approach it all. But you all are giving me some good food for thought. I think I have pretty much decided on a vibe tumbler for my first.. I will not be cutting stones for a long time, so will have to be content with pebbles I find until I get a saw. Had a try with a 4 lb sledge today, only a short time to aching arm and only 2 of 4 small stones broken into smaller pieces. Learned what not to do real quick! So using a vibe will let me just smooth the natural shapes some and put some shine on most pieces, even if it isn't mirror like in all cases. Gotta start someplace. Meantime I can hoard the larger stones for future dealings, be they trades or waiting for a saw. thanks for all the help so far. more questions soon, I am sure. mean time I want to see more of that beautiful granite! : )
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,159
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Post by jamesp on May 16, 2014 18:38:59 GMT -5
Here is a piece of Georgia granite. Will take a large tumbler. It is boring though. Looks like this:
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Geoff
spending too much on rocks
Please add 1074 to my post number.
Member since December 2012
Posts: 446
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Post by Geoff on May 16, 2014 19:15:46 GMT -5
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Post by snowmom on May 17, 2014 3:43:59 GMT -5
whoa James P, not with that beautiful mural carved into its side. Looks like a postage stamp on it, doesn't it cause the thing is so huge? And I know that is a gigantic mural! I can see lots of colored streaks vertically down its side, I suppose from water runoff over the ages? That Is one awesome hunk of rock... it must have a name? Do you live near there, and did you take the photo?
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Post by snowmom on May 17, 2014 3:46:12 GMT -5
Geoff V2.0 I love eggs! Sometimes I find them on the beach perfectly rounded... I bring those home if I can hold them in my hand like that one. That one has a lovely shine on it... came out perfect! That's what I'm aiming at!
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,159
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Post by jamesp on May 17, 2014 8:46:32 GMT -5
whoa James P, not with that beautiful mural carved into its side. Looks like a postage stamp on it, doesn't it cause the thing is so huge? And I know that is a gigantic mural! I can see lots of colored streaks vertically down its side, I suppose from water runoff over the ages? That Is one awesome hunk of rock... it must have a name? Do you live near there, and did you take the photo? Just the town of Elberton produces a third of all the nations monumental granite production in NW Georgia. Then there is road gravel operations using granite. Four quarries within 10 miles of my home here in south Atlanta. When they built the 4th runway at Hartsfield Intl Airport the constructed a 5 mile long conveyer system from the closest quarry. Here is interesting link on Elberton monument industry. it is a small town with 10-12 foot granite saws in every direction. like a lapidary factory for giants. Galvanived sheet metal clad open barns scattered everywhere. quarriesandbeyond.org/articles_and_books/elberton_granite_indus_flourishes.htmla closer view of the carving on 'Stone Mountain' :
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tkvancil
fully equipped rock polisher
Member since September 2011
Posts: 1,546
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Post by tkvancil on May 17, 2014 17:49:13 GMT -5
I posted these some time ago. Had to edit the photo so the color is a little richer than in person but close.
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