Mike I am new at rock tumbling also. I have Petoskey stones also. I read that since they are a soft stone you have to be real careful. The book told how to polish by hand. I tumbled mine for about 24 hrs. I used a medium grit. By looking at them, I am afraid to put them back in the tumbler with the polish compound. My plan is just spray them with lacquer. I haven't done it yet. Hope this helps. I am sure someone who has more knowledge and maybe has tumbled Petoskey stones would have more info then me.
I also have what you call 'soft Petoskey stones'. I know those cannot go in the tumbler or be hand polished. The book tells me just to put them in a pretty jar with some mineral oil. I was thinking about trying to spray just one of them with the lacquer and see what happens.
Mike, petrosky stone, as far as I know is a calcite. The coral it originates from has not gone mineral transfer. Of the few petrosky stones I have tumbled, I have so degraded the stone with all the polishes I was left with very little. A stone polisher I know, saves the final polish for the petosky stones after he cabs the original shape. He routinely mass final polished all his cabs I have never been able to final polish my cabs so I use a leather buff and cerium or tin oxide. I suggest if you have some choice samples, put them aside. Larimar is also similar. Do not tumble Larimar. If the only way I could polish petrosky stone was to tumble, I would do 220 for a few days, checking constantly. I would move up to 660 for a week, and run at least two weeks with cerium oxide. There might be some non mineralized organics trapped in the centers of the coral cells. Watch for gas build up. I once tumbled some fossilized buffalo scat and the tumbler had a soupy green mixture. There was no odor, but I suspect the mineralization was incomplete deep into the stones. It leached out with the tumble. Just my perspective on this. I often wondered if the reason the petrosky stone is localized to the Great Lakes region and not near ocean shores is the wave activity and the softness of the stone. If some seem agatized tumbling might work. Just keep a watch on it.
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hello its mike i just started my pre polish on my petoskey stones i did what you all said and that seams to work fine i left them in 14 houres with 300 then went to 400 ...14h. then 600. 14h. not done yet but they sure look prety good.... ;D thanks for all the help. ......mike
wampidy: Damn that is one beautiful piece of the earth AND I DIDN'T EVEN GET TO HOLD IT. You were too smart for me. lol
Oct 12, 2014 21:07:58 GMT -5
hornseeker: Just plugged in my QT12 and am tumbling my first batch of rock!!!
Oct 12, 2014 22:50:06 GMT -5
Fossilman: Slabbing rocks today.............
Oct 14, 2014 14:01:10 GMT -5
hornseeker: Wish I was...need a saw!!
Oct 14, 2014 14:44:09 GMT -5
drocknut: Lol, Jim. If I had let you hold it I would never have gotten it back. You did get to see it close up.
Oct 15, 2014 11:38:26 GMT -5
mr.mohs: cut it in half & share
Oct 15, 2014 20:34:58 GMT -5
wampidy: no no no I have no claim to it. She found it fair and square.
Oct 15, 2014 21:08:25 GMT -5
mr.mohs: o.k. I was just playing the role of the Judgment of Solomon...mostly
Oct 15, 2014 21:51:03 GMT -5
Shotgunner: You guys just stop bickering over a little blue rock. sheesh!!
Oct 18, 2014 12:00:43 GMT -5
mr.mohs: grinder where you taking us?
Oct 19, 2014 9:25:02 GMT -5
rocktard: OK, ....where is my listings, I tried to add my pictures using the add attachment, it kept on saying the file was to big.
Oct 19, 2014 9:32:00 GMT -5
kimx5: Need help..have done everything to the rule week after week ...just took stones out after polishing process ...they look lovely while wet but they lose their shine when they dry out ...what have I done wt
Oct 19, 2014 12:29:56 GMT -5
kimx5: Ooopppss. ?.what have I done wrong I was going to ask ?
Oct 19, 2014 12:31:59 GMT -5
Fossilman: kimx5-go to the "Total Rock Tumble" site on this forum,you will get tons of help there...Not many people visit the "shout" page....Thumbs up
Oct 20, 2014 9:36:32 GMT -5
mr.mohs: only the mostly...mostly
Oct 20, 2014 10:51:57 GMT -5
Fossilman: He said he would,I said he wouldn't,but they thought he did,it turned out,he could have..............LMAO
Oct 21, 2014 9:15:14 GMT -5
hillquist: Just wanted to to the guy that was wondering about the Hillquist saw, it's a great saw, I have the 16 inch slab saw RF-14-16, the original Hill
Oct 23, 2014 20:09:45 GMT -5