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
thesterlingseraph: Hello, I am hoping someone here can lead me in the right direction. I have a 4.5" circular slab of very rare bright green Victoria Stone/Imori I am looking to sell. Does anyone know anyone who specializes in Victoria Stone? The slice is from the 1960's-70s
Sept 1, 2014 20:05:32 GMT -5
kk: thesterlingseraph Please read the forum rules and associated sediments about selling here. Thus far you have not even introduced yourself, how can you expect someone even bother to answer your request in any form or way?
Sept 1, 2014 21:24:07 GMT -5
Fossilman: KK speaks for all of us too!
Sept 1, 2014 21:59:21 GMT -5
wampidy: Forum is going crazy today. Posting is almost impossible and when it does go through it puts up two or three copies. Spoiled I guess, we have not had any problems for quite a while.
Sept 1, 2014 23:14:40 GMT -5
glennz01: is someone hacking the site?
Sept 1, 2014 23:16:33 GMT -5
glennz01: I cant even access some topics
Sept 1, 2014 23:17:22 GMT -5
wampidy: The guest poster is me.
Sept 1, 2014 23:17:35 GMT -5
glennz01: I thought you couldn't post as a guest
Sept 1, 2014 23:22:02 GMT -5
glennz01: If anyone knows what a good price is for selling tumbled stuff please send me a pm.... I'm currently only thinking about $4/ lb (thinking about selling to local gift shops)
Sept 1, 2014 23:24:48 GMT -5
glennz01: A new record... the site posted my thing in 4 posts!
Sept 1, 2014 23:33:22 GMT -5
glennz01: whos going to fix it
Sept 1, 2014 23:33:39 GMT -5
Fossilman: No problem on my end with the forum..
Sept 2, 2014 9:35:23 GMT -5