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Post by scared0o0rabbit on Nov 23, 2009 21:59:12 GMT -5
I'm pretty new to tumbling. I've got a Thumler model T to work with, but I don't have a lid for my barrel, so I've been using a makeshift barrel until I've got a few bucks to order a new lid for the barrel.
I've found more information in reading from this forum this evening then I've ever seen before on rock tumbling, but I still had a couple of questions. I tried using the search function, but it just gave me error messages saying it had timed out.
First, am I going to have any lucking tumbling, shaping, and polishing serpentinite (http://en.wikipedia.org/wiki/Serpentinite) or should I give up on it? I really like the way serpentinite looks, so I'm hoping to have some luck at it. Is serpentinite just too soft to tumble?
Second, is it it okay to use play sand as an initial step to help save on needing to buy 60/90 grit? From what I've read serpentinite is fairly soft, and I have tumbled with play sand for about a week now and am noticing considerable shrinkage in my initial stones, but is the sand going to end up causing harm to future efforts to polish these stones? From what I understand, sand is pretty soft too, so even if it's okay to use for these rocks, am I going to find it worthless on harder types of rocks? I've got about 70 pounds of play sand laying around right now that it'd be nice if I could use.
One final question, does anyone have suggestions of places to go to collect neat rocks for tumbling in Northern California/Southern Oregon or for places to buy rock tumbling supplies for cheap?
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Minnesota Daniel
freely admits to licking rocks
A COUPLE LAKERS
Member since August 2011
Posts: 891
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Post by Minnesota Daniel on Nov 23, 2009 23:18:08 GMT -5
Play sand is quartz, which has a hardness of only 7, and it's probably not very sharp edged either, so I don't know how useful it would be for tumbling. Serpentine is soft though, so it might work, but you have no control over grit size or impurities, so it's not a very elegant solution. Nevertheless, if you've got 70 pounds of play sand laying around I suggest you get out the ShopVac before you do anything else.
I've seen this question asked before, so maybe someone else might have experience with sand and can share that with us (without being a smart a*s like me).
Danny Boy
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Sabre52
Cave Dweller 
Me and my gal, Rosie
Member since August 2005
Posts: 20,497
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Post by Sabre52 on Nov 23, 2009 23:26:27 GMT -5
Serpentinite is one of those mixed hardness materials with a lot of cleavage planes and usually won't tumble worth a darn. Just pocks and undercuts and is hard to shine. For starters, I'd go with quartz minerals like agate and jasper both of which are available in quantity in northern Cally and southern Oregon along almost any stream. They're harder and will take a nice polish with just standard tumbling methods.....Mel
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Post by scared0o0rabbit on Nov 23, 2009 23:44:19 GMT -5
Thanks for the quick reply.
That's really a shame about the serpentinite because it is a really neat looking rock, and I happen to live about 5 minutes from a mountain of it heh.
As far as the play sand goes, I think it's only worked like it has for the serpentinite because of how soft it is. I've only got 2 chunks of it in with a mix of random other rocks right now and it's decreasing in size MUCH more rapidly than the other rocks. One of the two pieces I noticed a crack in this evening so it won't be a keeper, but the other one I have seems to be rounding to some degree, so we'll see if I'm able to polish it up at all (I just can't help trying, the rocks are so unique looking).
I really need to get my hands on some actual grit pretty soon, because if I tumble the serpentinite with playsand much longer I won't have rocks left at all lol.
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Post by Toad on Nov 24, 2009 6:55:12 GMT -5
Yes, use actual silicon carbide grit - it is a 9+ on the moh's scale and will provide much better cutting action - on the appropriate rock. Your sepentinite probably would have been reduced to sludge.
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Post by johnjsgems on Nov 24, 2009 7:52:30 GMT -5
If you are tumbling the serpentine with harder rocks they are helping round off the serpentine. They will be completely gone if you let them run. Serpentine on the beach rounds off nicely with sand and rock but how long does it take? If you run a batch of only serpentine with 60/90 it should round off pretty fast. Getting a nice polish will be another thing.
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docharber
has rocks in the head
Member since October 2008
Posts: 716
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Post by docharber on Nov 27, 2009 21:39:20 GMT -5
I read an article in an old Lapidary Jou7rnal recently about Puerto Rican serpentine.. The author commented that it tends to weather to a very soft, crumbly material that is basically useless for lapidary purposes. that may account for at least part of what Mel was talking about. The degree of weathering would dramatically affect the hardnessx of the material and some components of the rock may weather faster than others, as this is a stone of highly variable composition and may contain admixtures of several serpentine group materials.
I have some fairly solid lime serpentine that I have been able to get a fair polish on when cabbing, but in the tumbler I doubt it would do so well. It tended to chip just abit when cabbing and that's jin the case of fairly good grade material. I have had trouble getting a polish of other soft stones, too- notably obsidian and sodalite. I don't mix stones of differing hardness and I use lots of clean plastic pellets in polish and separate pellets for prepolish. I read someone's comments that a prepolish in 1000 grit might help and I'm planning to give it a try. i have some fluorite and blue massive appatite I want to try, using the same method. Good luck with you tumbling, and welcome to the forum!
Mark H.
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rallyrocks
fully equipped rock polisher
Member since November 2005
Posts: 1,507
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Post by rallyrocks on Nov 28, 2009 0:24:44 GMT -5
Thing is- "serpentinite" is not one specific mineral but rather a name that applies to several different materials that share having undergone similar geologic processes.
Some serpentines make for great carving material since they aren't terribly hard, but as Mel was mentioning, many types of serpentine are crumbly, flaky and pretty much useless for any lapidary purposes, since the name covers such a wide range of stuff- it really boils down tho the nature of the specific material.
If you are up in the Klamath river area, there are some good serpentinites that can be successfully tumbled to a point- being as soft as it can be or mixed hardness- getting a good polish on them can be elusive, but I've gotten some really pretty "satin finished" stones tumbling serpentines from up there, however, as others have mentioned, they really aren't the best materials for tumbling- especially for someone new to the whole tumbling process.
Gaumer's lapidary museum and store in Red Bluff is among the best rock shops in the state, if that's too far to travel, The Rock Shed in South Dakota is a really great internet/mailorder supplier.
Southfork Mining is out near Happy Camp and I think we have a few other members on the board here that live up that way.
Oh I just saw on another thread that you've already done business with the rock shed, and you're by Chico- Stony Creek above Black Butte res is a good place to collect some nice colored jaspers, and you should check out the club that ran the tumbling contest...
Feather River Lapidary and Mineral Society in Oroville, should be a great resource for you.
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