1Mark
noticing nice landscape pebbles
Member since November 2004
Posts: 91
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Post by 1Mark on Dec 14, 2008 23:18:22 GMT -5
I bought 5 pounds of Labradorite to try a few weeks ago. I filled a 3 pound rotary barrel with it about 2 weeks ago and started roughing it. It's still running and should be ready for the vibe in a few more days. I also stuck some of the remainder in my model B and roughed it along with some mixed agates and granite. That part went fine, but now that I'm in 500 grit in the Lot-O I'm seeing some pits and gouges in it.
I take it that Labradorite needs to be run by itself (or with other stuff that's softer than agates)?
Mark
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DeanW
has rocks in the head
Member since December 2007
Posts: 721
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Post by DeanW on Dec 15, 2008 3:06:22 GMT -5
My understanding is that Lab is mixed-hardness and thus undercuts very easily. I don't recall if I've ever seen it tumbled.
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rollingstone
starting to spend too much on rocks
Member since July 2009
Posts: 236
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Post by rollingstone on Dec 15, 2008 4:45:02 GMT -5
Labradorite is Mohs 6 hardness and is best run on its own or with other Mohs 6 stones. If you need to run it with something like agate, use pellets to cushion things, even in coarse grind. Actually, that's not a bad idea even if you run it by itself, because Labrodorite has a sharp cleavage plane and will want to flake off and pit in one direction. Since the "flash" is only in one plane, it mostly looks like shiny gray stones when it's done, but if you move it around in your hand until you find the proper direction, it gives that nice bluish flash when tumbled. Here's a couple shots of some I tumbled in a rotary a few years ago: -Don  Now you see it:  Now you don't:  |
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ejs
spending too much on rocks
Member since July 2008
Posts: 478
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Post by ejs on Dec 15, 2008 9:25:45 GMT -5
I have tumbled Labradorite in my Lortone 3#ers and have had the troubles you describe. In one case, it tumbled all the way to the burnish and then got trashed in the very last step! That bummed me out. Next time I try it, I will definitely tumble it by itself and use a lot of cushioning.
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1Mark
noticing nice landscape pebbles
Member since November 2004
Posts: 91
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Post by 1Mark on Dec 16, 2008 11:32:58 GMT -5
Thanks for the feedback. After I get my current load out of the vibe I'll try running the stuff I roughed in the 3# rotary using 4mm ceramic spheres as filler in the Lot-O.
Mark
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WarrenA
fully equipped rock polisher
Member since November 2003
Posts: 1,530
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Post by WarrenA on Dec 22, 2008 0:22:57 GMT -5
I bought some labradorite a couple of years ago and started to cut it up to cab it and did a couple of pieces and noticed that it didn't flash very well and then discovered that I needed to cut it so that the flash was most visible when viewed as a pendant. That took an assistant to help hold the rock so I could figure out which way to cut it.
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