mooresean68
having dreams about rocks
Member since February 2018
Posts: 52
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Post by mooresean68 on Nov 25, 2018 15:44:35 GMT -5
Hi All, Looking for suggestions, hints, advice on two types of minerals. First is labradorite, I know it's known to be a hard materaial to tumble especially for a newbie but I'm going to give it a go. Is there anything out of the ordinary to address on this type of material? The second is around the image below which I believe is metamorphic. Any suggestions on handling the undercutting? Thanks -Sean
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hnhstngs
noticing nice landscape pebbles
Member since September 2018
Posts: 93
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Post by hnhstngs on Nov 25, 2018 18:15:52 GMT -5
I'll be interested in seeing what tips there are for the Labradorite. Got half a dozen pieces in coarse shaping right now.
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Post by MsAli on Nov 25, 2018 20:33:08 GMT -5
Hi Sean and welcome from Fresno California Theres a thread somewhere on it I personally have not even attempted tumbling it yet, but have tried cabbing it and I sucked. It's a tough one Found one for you forum.rocktumblinghobby.com/thread/36957
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mooresean68
having dreams about rocks
Member since February 2018
Posts: 52
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Post by mooresean68 on Nov 25, 2018 20:52:04 GMT -5
MsAli Thanks from Whidbey Island WA! I've actually been lurking around now for a little while.
Read up on that thread thank you that will come in handy! And it looks like there can be really nice results to be had too!
-Sean
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Post by MsAli on Nov 25, 2018 22:50:58 GMT -5
MsAli Thanks from Whidbey Island WA! I've actually been lurking around now for a little while.
Read up on that thread thank you that will come in handy! And it looks like there can be really nice results to be had too!
-Sean
Tumbled lab can be really amazing. Cant wait to see your results
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SirRoxalot
freely admits to licking rocks
Member since October 2003
Posts: 790
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Post by SirRoxalot on Dec 8, 2018 17:40:02 GMT -5
Feldspars have perfect cleavage that can make them a real pain to tumble. Depends a lot on your material.
The more work you put into sorting and nipping the cracks out, better your results.
Gentle is the key. Use tons of smalls, or a thickener, or a slower rotation, or overload the barrel, whatever it takes so that they're not impacting hard.
You have to keep sorting, at every stage. Leave the cracks in and you'll find they gleefully trap grit.
The cracks also produce lots of weak bits that are just thrilled to spall off, right up to polish, producing sharp edges which ruin the batch. Thin or pointy bits love to break. Test thin bits with finger pressure, if you can break it, chuck it. Got to get the cracks out!
Watch for intergrown quartz, it's harder and can cause problems.
No special grit regimen, AlO polishes nicely. I do coarse in rotary and the rest in vibes. I've run various colors of feldspars, they're pretty but a pain, and I suspect labradorite is about the worst of the bunch. Even the best of it, from Finland, can be rife with cracks, and heartbreaking.
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mooresean68
having dreams about rocks
Member since February 2018
Posts: 52
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Post by mooresean68 on Dec 8, 2018 21:13:23 GMT -5
SirRoxalot, thanks! great info there I appreciate it. I have a feeling they're running a little rough right now in stage one and plan to recharge them tomorrow. Hopefully I won't find chunks
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fireforged
starting to spend too much on rocks
Member since December 2015
Posts: 215
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Post by fireforged on Dec 8, 2018 21:15:15 GMT -5
I have never had good results trying to tumble labradorite.
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zrock1
off to a rocking start
Member since January 2016
Posts: 24
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Post by zrock1 on Dec 9, 2018 15:43:26 GMT -5
My little girl is tumbling some lab right now. We over loaded the drum for course grit and they turned out good so far.. some had yo go back for a second round... she is super excited to see them finish.. probably could have gotten them done first round but did not realize belt was slipping
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mossyrockhound
fully equipped rock polisher
Member since January 2011
Posts: 1,278
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Post by mossyrockhound on Dec 9, 2018 16:13:04 GMT -5
Looks like some good advice on the lab. It will be interesting to see how yours turns out.
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mooresean68
having dreams about rocks
Member since February 2018
Posts: 52
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Post by mooresean68 on Dec 9, 2018 17:47:17 GMT -5
Update: 2018-12-09
Well cleaned out the lab in a 6lb lortone barrel after 8 days in 60-90 SiC. Result: they go back in.
Lot of fractures which I'm not terribly surprised about but what did surprise me was the loss of volume. The barrel was over 3/4ths full at the start, but what goes in goes back in, and that was less than half. So almost if not a full quarter volume lost in about 8 days. I think that loss of volume lead to more movement and clunking around causing a lot of the fractures. This time I'll keep my eye on it and listen for movement and see if I need to add filler.
-Sean
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