bpaul
off to a rocking start
Member since December 2009
Posts: 21
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Post by bpaul on Mar 4, 2010 0:44:08 GMT -5
So I have been unable to shake this desire to tumble some malachite. Not sure exactly what the problem is and I thought the urge would start to fade as I waited for a batch of lakers to finish, but it has only grown stronger. So I'm about to take the plunge, buy some rough, and get rolling (literally).
I had a few questions I thought the kind folks on here would be able to help me with before I got started.
First, I've noticed the only other stone that has a Mohs hardness of 4 and is commonly available for purchase is flourite. For some reason however, I seem to remember reading that you really shouldn't tumble flourite with other stones. Is this true? I'd like to get a few pounds of malachite and tumble it with far less expensive other stone. Any reason combining flourite and malachite would be a problem. Also, can anyone suggest any other less expensive stone, besides flourite, that I could tumble with malachite.
Second, I have read quite a bit about how difficult it is to get a good shine with malachite. I would love to hear suggestions about what polish would be best to use. Obviously, a polish that works well with softer stones is appropriate. But I'm looking for specific suggestions if anyone has them.
Thanks in advance for any help.
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Post by johnjsgems on Mar 4, 2010 9:29:54 GMT -5
I'll send you a sample of Chrome Oxide if you will try it and let me know if it works. I've heard it is the "magic ingredient" n Zam. Zam works on a buffing wheel so Chrome Oxide should work in a tumbler. I'd really like to know if you would lie to try it. As far as a mix, I think I'd stick with other copper minerals like turquoise or Chrysacolla but I don't know why.
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Post by Toad on Mar 4, 2010 11:06:37 GMT -5
I don't see any problem in mixing malachite and fluorite - but I have never polished either. I would make sure that you include lots of cushioning in your loads though.
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Post by susand24224 on Mar 4, 2010 11:56:05 GMT -5
Malachite is considered brittle, and I don't know about flourite. My experience is that the brittleness of a particular rock matters as much as the hardness. In other words, with the malachite being brittle, the flourite may cause it to chip, if the flourite is not as brittle.
I've had good luck rotary tumbling turquoise with 50% ceramic shapes and 50% turquoise. It wears down *really* fast though, so throw out the rules about not needing to check the tumbler for seven days. I'm not sure I would put something this "wearable" in a vibe, but I don't have much vibe experience so am hesitant about anything that's a bit different with it.
For me, the key to softer stones is *lots* of time in polish. I haven't tried chrome oxide though, so I would eagerly accept johnjsgems's kind offer.
Susan
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bpaul
off to a rocking start
Member since December 2009
Posts: 21
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Post by bpaul on Mar 4, 2010 19:52:22 GMT -5
Thanks for the replies. I'd be more than happy to try chrome oxide when it's time to polish. Let me know what you need if you really are willing to send some along, johnjsgems.
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Post by johnjsgems on Mar 4, 2010 20:38:06 GMT -5
Just PM me your name and address and I'll 1st Class Mail a sample. By the way, I met with the owner of Tagit Co. (makers of the Gyroc tumblers). His grit kits (for his vibes) includes a polish mix that is light green. I said secret formula looks a lot like chrome oxide and aluminum oxide mixed. His reply "and cerium and something else". Guess he covers all bases with a "smorgasboard". Said it works great on apache tears by the way. If you have a good aluminum (.5 micron or finer) you might want to try blending it. Chrome oxide is really nasty stuff. It is the only polish I package wearing gloves and still end up with green fingers.
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tomcloss
starting to spend too much on rocks
Member since October 2008
Posts: 158
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Post by tomcloss on Mar 9, 2010 22:21:05 GMT -5
Malachite is one of my favorite stones. I've tumbled it and I always end up hand polising the stones by hand after I tumble them to get the shine I want. I always tumble it by itself. The my avatar image is a piece I've tumbled. Malachite is about 3.5 on the Mohs scale so If I had to tumble it with something I'd try calcite which is 3 to 3.5.
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techmotive
off to a rocking start
Member since April 2012
Posts: 1
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Post by techmotive on Oct 10, 2012 22:03:51 GMT -5
I had a HUGE rough malachite stone from Zaire and I broke it apart as best I could for tumbling, and I am about to tumble a soft beautiful stone for the first time... It's scary! lol. It's a full load of malachite in a 15 lb rotary tumbler so I'm not worried about other stones affecting it. I think I'm going to start with 80 grit and run it for a few days, checking frequently, and then go to 220 until they are at the desired shape, and then polish. As for the chemistry involved with the polish, the internet has answers that are all over the place.. has anyone figured anything out yet? Any tips? I have cerium oxide which is what I planned to use but now I'm hearing of these wonderful mixes that people swear by.... help! haha Thanks guys!
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Post by johnjsgems on Oct 10, 2012 22:44:32 GMT -5
I'll be polishing some soon in a vibe using .3 micron aluminum. I'll let you know how it turns out.
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