custommike
starting to shine!
Member since November 2012
Posts: 42
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Post by custommike on Nov 15, 2012 12:46:16 GMT -5
Hello all, first post here and relative newbie to the hobby. I purchased a harbor freight 3lb tumbler a few months back and instantly got hooked! I have done 2-3 pretty successful tumbles where I have gotten a great shine out of the rocks. So I decided to try something new and bought a couple pieces of aventurine from a local shop. I didn't get enough for a full cycle so they went in with other stone I had going. At any rate I started with 60/90 went to 220 then to 400 then polish. All of the stones polished up nicely, including some white quartz I had except the aventurine. the aventurine ended up looking like it just came from 220, no shine and even trying to posh by hand didn't work. I read that aventurine is quartz, so shouldn't polish the same? Thanks for the help!
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Minnesota Daniel
freely admits to licking rocks
A COUPLE LAKERS
Member since August 2011
Posts: 891
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Post by Minnesota Daniel on Nov 15, 2012 19:05:47 GMT -5
Welcome Mike,
You are not alone, one of my first attempts at tumbling was aventurine too. I did it by itself and I couldn't get it to polish. It came out much better than the 220, but not really polished. Then I tried a different polish, the Rock Shed's polish. Came out better, but still not really polished. I got fed up and just let it run for another ten days. That did the trick. Don't add more polish, just leave it in longer and see what happens.
I've done it with quartz too, and up to the polishing stage, they seemed about the same. When the quartz was finally polished though, the aventurine still looked pretty dull. I had a problem with the aventurine getting frosty on the edges too. That problem I think I resolved by adding more small material, and removing some other rather big pieces of rock and leaving it in the polish longer. You might try that too.
Other people probably understand aventurine better than I. Don't give up, you'll get it eventually.
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Post by johnjsgems on Nov 15, 2012 20:36:22 GMT -5
Back when I was young and the rocks were still a little warm, aventurine was a green quartz. Now you see every color "aventurine" and I suspect the People's Republic is producing it. Kind of like "new jade" and all the other "enhanced" rocks. A longer polish cycle couldn't hurt.
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Minnesota Daniel
freely admits to licking rocks
A COUPLE LAKERS
Member since August 2011
Posts: 891
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Post by Minnesota Daniel on Nov 15, 2012 21:13:29 GMT -5
Back when I was young and the rocks were still a little warm, aventurine was a green quartz. Now you see every color "aventurine" and I suspect the People's Republic is producing it. Kind of like "new jade" and all the other "enhanced" rocks. A longer polish cycle couldn't hurt. The first aventurine I tumbled was from the Rock Shed and looked very much like peachy quartz, but you could see it wasn't exactly quartz, and it sure didn't polish like quartz. The next batch was green aventurine and it really did look like a cross between feldspar and quartz - very distinct cleavage planes. Right now I have some that looks like a cross-section of an intrusion or seam. The outside of it is very flakey, so much so that I'd call it feldspar. The middle of it though looks pretty much like quartzite. It came directly from Ontario.
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custommike
starting to shine!
Member since November 2012
Posts: 42
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Post by custommike on Nov 15, 2012 21:59:39 GMT -5
What about doing an additional stage of 1000 grit?
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Minnesota Daniel
freely admits to licking rocks
A COUPLE LAKERS
Member since August 2011
Posts: 891
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Post by Minnesota Daniel on Nov 15, 2012 22:19:19 GMT -5
Mike,
I have heard that recommended for softer rocks like Labradorite, but never aventurine. Maybe someone else has an idea.
Dan
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snuffy
Cave Dweller
Member since May 2009
Posts: 4,319
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Post by snuffy on Nov 15, 2012 22:48:28 GMT -5
I've tumbled quite a bit of it.I always go 3 days in 1000 in a Loto after coarse,then to polish as I do all my tumbles.One thing I have noticed on the orange-peachy stuff,it seems to be a different material,I have white frosted edges sometimes on it. It doesnt have the aventurescence that the green and others do,which gives it the name. snuffy
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jspencer
freely admits to licking rocks
Member since March 2011
Posts: 929
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Post by jspencer on Nov 15, 2012 23:54:15 GMT -5
I have polished self collected mostly red aventurine from east of Austin. It may be just blind luck but had no problems polishing it with other quartz rocks and flints and jaspers from the area. i used the rotary for smoothing. About 3 weeks in double 3 lb. barrels of 60 grit. Then 3 days each of 220 and 600. This may be the difference, I also used an AO prepolish for 3 days and then 5 days in Raybrite A followed by a Borax burnishing.
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Post by johnjsgems on Nov 16, 2012 10:20:30 GMT -5
A pre polish run in Tripoli would probably not hurt either.
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marinedad
freely admits to licking rocks
Member since December 2010
Posts: 813
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Post by marinedad on Nov 17, 2012 0:16:43 GMT -5
custommike, are you using plastic pellets in the last few stages?
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jspencer
freely admits to licking rocks
Member since March 2011
Posts: 929
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Post by jspencer on Nov 17, 2012 22:46:10 GMT -5
Oops, I forgot to mention that I did all the stages in a vibe after the initial 60 grit tumble.
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custommike
starting to shine!
Member since November 2012
Posts: 42
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Post by custommike on Nov 26, 2012 11:51:59 GMT -5
I will be using plastic pellets in the polish stage. I only have one rotary so what I do is get a good amount of stones through each stage, that way I have enough to fill the barrel at each stage.
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darticus
off to a rocking start
Member since September 2019
Posts: 4
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Post by darticus on Nov 1, 2019 21:07:44 GMT -5
My green turned up with white frosted edges. New to this. What should I try? Thanks Ron
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Post by rmf on Nov 2, 2019 6:00:42 GMT -5
Aventurine in its various colors is a quartzite. Note the mica in it. So unless it is mislabeled it is quartz. However aventurine is quartzite so it is not as tuff as agate and needs to have more cushioning than agates and jaspers. Normally in a 3# tumbler drum you can tumble then together and no problems. However this may depend on the the amount of fines you have in the drum and how full the drum is. Where most beginners have problems is with the Lortone 3# is the pics in the book imply the tumbler is 50% full. the drawing is there just to show what is going on inside the drum not to show how full the drum should be. When you start tumbling rocks in coarse grit The drum is 85% full. By the time the drum is done with coarse the drum is usually 60% full of rock and the rest of the rock is mud. If you finish with out adding more rock or a filler then the tumbling action is dropping the Aventurine too far and it is chipping (because it is not tough). You can see this is the problem most clearly when you get a stone that is polished except for the corners being frosted. In your case try doing two batches of rock in coarse then when you go to the take half of the second batch and use it to fill up the first. This will keep your tumbler full enough you should not have that problem I mentioned. You should have about 25% of the tumbler load that is <1/2". These fines act a cushioning.
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MommaGem
spending too much on rocks
Member since April 2019
Posts: 312
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Post by MommaGem on Nov 13, 2019 10:07:42 GMT -5
To follow along from rmf's post - the mica content in the Aventurine can have a varying affect on the final polish. There are little flecks of mica throughout and it is much softer than the quartz portion. So if the mica that is on the surface has undercut, it's going to leave the surface too rough to get a good polish. I had a horrible time getting a polish on some purple aventurine, but had a great experience with green aventurine - it all depends on the amount of mica in your specific batch of rough.
All that said, I did add a 1000 grit pre-polish stage to my tumbling and that seemed to help quite well. Maybe it will help for you?
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