grizman
freely admits to licking rocks
Member since July 2011
Posts: 878
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Post by grizman on Jan 6, 2015 14:48:43 GMT -5
I have been working on this project of trying to polish the Brazilian Garnets I purchased from the Rock Shed. They are relatively rounded for the most part, but have a very rough exterior finish, like they are "crazed".
I ran the batch for one full month in 46-70 grit with assorted agates and jasper, but after a month, I had nicely rounded agates and jaspers, but other than size reduction, the garnets looked the same!
Has anyone had success in getting a smooth finish on Brazilian Garnets so that they could be polished? If so, what did you do? I need LOTS of help with this project I have taken on. I know they are a little harder than agate for the most part, but about the same as the jaspers and very dense.
Maybe they are one of those gems that you never get smooth enough for a polish? Please jump in with suggestions or success stories. Obviously, I know not what I am doing!
I am using a rotary until I can get them smooth and then hope to go to the vibe.
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,154
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Post by jamesp on Jan 6, 2015 16:00:52 GMT -5
Starguy tumbles them. Most garnets are about equal to most quartz in the mohs department, but some much tougher. You say you have a size reduction with the garnets, are you saying that you are getting a polish on the agate and not the garnets ? Do you know if they are almandine garnets, or the type ? Garnets range in hardness from 6.5 to 7.5, some claim 8. If you are tumbling hard Montana agate with softer 6.5 hardness garnets you may not get a polish, but that would be a surprise. The harder stones often steal the polish. Garnets usually friendly about taking a polish.
Then again, they may be really hard and the 220 or next stage is having a hard time removing the 46-70 scratches, but it took care of them on the agate/jasper.
Stones with different mohs hardness can be tricky. What color are they, another issue, because they come in every color. So ID is difficult too.
You got to get them polished, I want to see them.
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Post by 150FromFundy on Jan 6, 2015 17:05:31 GMT -5
I tried a few of The Rock Shed garnets in a mixed tumble with little success. The garnets reduced in size but would not round or smooth enough to move on to Stage 2 (120/220). The garnets appeared to reduce in size by chipping, rather than grinding down. Sounds similar to your experience with them.
Note that this is CRUSHED almandine garnet. The fact that it is possibly extracted by blasting and then crushed to size may be internally fracturing the garnet and it may simply chip rather than polish.
I will try a dedicated load of the garnets with pellets for cushioning the next time around.
Darryl.
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,154
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Post by jamesp on Jan 6, 2015 18:28:21 GMT -5
I have tumbled Georgia almandine garnets in a rotary with no problem. They are ugly and full of iron, but whole, and eroded out of schist.
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grizman
freely admits to licking rocks
Member since July 2011
Posts: 878
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Post by grizman on Jan 6, 2015 19:22:04 GMT -5
Hey, thanks folks for the feedback. I am not quite as bummed out with my efforts. I have pretty good luck with most of my tumbling efforts, but these Brazilian Garnets have got me beat...at least for the time being. I will keep working with them until I have success or garnet dust! Yes, I will post pictures "if" I have any success with my polishing efforts. Please do not hold your breath!
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