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
jakesrocks: LOL. The bad pain comes tomorrow when the tacos start coming out the other end.
Apr 23, 2015 22:51:40 GMT -5
mr.mohs: Old El Paso///en su mayoría™
Apr 23, 2015 23:18:56 GMT -5
rockpickerforever: What kind of tacos you eating, Don? Or are you referring to the hot sauce? Supposed to follow up hot stuff with ice cream. (C'moooooon, ice cream! )
Apr 24, 2015 9:22:55 GMT -5
Fossilman: Must have been some Habanero involved!!!! LOL
Apr 24, 2015 9:52:22 GMT -5
drocknut: Maybe he is too busy feeling the pain today yikes. Hope everything comes out alright for ya Don.
Apr 24, 2015 10:19:55 GMT -5
jakesrocks: LOL, had to get Jake to bring me a pencil so I could finish the paperwork. Had a big bowl of orange sherbet last night. Didn't help much. No Old El Paso stuff for me Ed. Real home made salsa with lots of jalapenos.
Apr 24, 2015 11:48:02 GMT -5
Fossilman: OMG me arden los ojos!!! Don....LOL
Apr 24, 2015 14:15:09 GMT -5
jakesrocks: Hey Ed, I used a red pencil, just in case.
Apr 24, 2015 14:17:39 GMT -5
jakesrocks: Hey Mike, just scored a killer chunk of gem dino bone, and a face polished hunk of pet wood from the Boron Dry Lake, Ca. area to add to my Boron collection.
Apr 24, 2015 14:19:48 GMT -5
jakesrocks: Hey Mike, no arden los ojos. More like Mi culo se quema. LOL
Apr 24, 2015 14:55:33 GMT -5
mr.mohs: glutmus Fuego ! chili today- hot tamale
Apr 24, 2015 15:09:31 GMT -5
Fossilman: Is it Mexican food week-I made Tijiuana crock pot pie the othe day......................But it's all right,everything came out ok!!!!!!!!!! LMAO
Apr 24, 2015 18:50:10 GMT -5
Fossilman: Don,did ya' post the dino bone and wood yet or is it coming in the mail?
Apr 24, 2015 18:51:01 GMT -5
jakesrocks: Hey Mike, I posted a link to the bone on the Theropod vs Sauropod thread. Just bought the danged things this morning. Probably be Tuesday or Wednesday before they get here.
Apr 24, 2015 21:09:11 GMT -5