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New User

Mar 14, 2008, 4:34 PM

Post #1 of 2 (137924 views)

     I have recently acquired uncleaned rocks from a Brazilian mine. They seem to have a layer of what I assume is dirt or sediment (or some soft rock) around the gem stones (I assume are in there).

The rocks need to likely be cleaned before they're smoothed and polished.

  1. My first question is, will a rock tumbler clean off the rock revealing the gem? Or is a tumbler for polishing/smoothing only?
  1. Secondly, the capacity of my tumbler is 3 lbs. and I think it holds a maximum of approximately 1/2 inch stones. Does this mean the gems inside, or the size of the entire uncleaned rock? Because I assume that after breaking down the soft rock on the only over sized rock I have to clean (2 inches approx.) I would be left with many smaller rocks that would fit the maximum capacity of my 3lbs tumbler adequately.
  2. So my final question is, can I place a large rock in by itself if it is over the normal capacity, if it's not a solid rock but most likely just hard dirt around gems in order to get the gems out which would be within the acceptable capacity to tumble with my other smaller rocks? Or do I have to buy a larger tumbler? (Keep in mind I'm poor)

Any help would be appreciated very, very much
Thanking you very much :)

New User

Apr 27, 2010, 5:28 PM

Post #2 of 2 (118801 views)
Re: [clownshoes] NEED HELP PLZ [In reply to] Can't Post

Here is a little trick I've learn over the past 4 years I've been tumbling..

First and foremost.. Clean your stones.

This can be done with warm soapy (ivory snow or borax) water in a mater of 2-4 days rotating the water and soap. In many cases you may need a tooth brush and what I prefer: "Dawn Foam" Just a tad of this foam with the tooth brush will loosen any deep deposits. But again in some cases you may need to repeat this step several times in order to obtain a good stones for the examinations period.

Once the cleaning and examinations process have been completed.. you may need to pre-tumble your stones once or even twice (without the use of grit or additives).. Stones should be pre-sized, pre-cut and pre-shaped before hand in order to achieve a well rounded stones and polish.. This means your ruling out any possible carry over contamination from one batch to the next. deep pits, cracks and seems often carry grit or even plastic pellets over to the next batch.

Next.. Once you've completed a few pre-tumbles, (basically rounding and smoothing some edges) you can now start the recommended tumbling process..
This process can take a bit more then one month to complete from start to finish..

The first step is to add the stones to the barrel.. typically a good size or starting barrel is the number "3" which I would for the middle stages of the tumbling and polishing.. Placing the stones in the barrel *At Least* half way to the top of the barrel as not to over fill with stones and thus casing the barrel and it's contents to be come unstable and not rotate as smoothy.

Next should be the water, most use simply tap water.. but I prefer to add something a bit more reliable.. Mineral, distilled or even filtered water.. is a great option in this case.

Pouring the water into the barrel and slightly cover the stones (bring the water to just above the stones) then add the recommended measurements of course grit.. Or 3 teaspoons. At this point the grit is resting on the stones and not at the bottom of the barrel.. I have heard other hobbyist complain about, their grit had settled at the bottom of the barrel and not mixed well with the contents.

This is why the grit should be added last just before closing the barrel.. Without moving the barrel, tightly affix the seal and top cover with your thumb screw.. Lift to it side and rotate as if your the spindles. This keeps the grit from adhering to the bottom of the barrel until placed on the tumblers spindles.

Place the barrel on the spindles (which should be rotating) and check for the rotation of the barrel.. this is the critical point.. is the barrel to heavy as not to allow for a smooth rotation?.. if there is any hesitation in the barrel or spindles.. remove the barrel reopen the seal and take a few stones out.. (this is why we do a pre-tumble beforehand) keep like stones (*hardness etc) that work well together in containers as you move through the process.

Once you have the above pretty well covered.. the rest is simply a matter of time.. Rotate, clean and even replace barrels every 7 days.. mark barrels accordingly, Course, medium, fine, polish etc.. and never get the barrels mixed up. This is one good reason you should have more then one barrel per tumbler..

After an alloted 7 days.. you'll need to clean out and store the slurry.. *Do Not* mix or filter the slurry in a typically sink or any sink.. This process should be preformed outside with the use of filters and several buckets of large plastic containers.

At this point (after examining and cleaning the stones) You may want to re-soak them in warm soapy water.. This will assure that they do not carry over contaminates to the next batch. Repeat the process above (but replace the course grit with medium or fine grit).. Follow suit on the barrel placement on the spindles and wait the 7 days..

At this point your probably thinking.. are you nuts.. I never realized it would take this long.. again most manuals recommend at least 7 days.. per tumblings.. But of course I've added a few steps and stages..

You've finally reached a point where you can start polishing the stones.. many will tell you, that you can use a verity of polishing compounds.. But I prefer cerium oxide. I have tried aluminum oxide before, but it tends to leave a milky haze on the stones.

It's recommended that you follow the directions as started above (barrel, stones, water, polish).. But I've altered my plans to include a "dry run" this means I've added walnut shells and the cerium oxide only no water. As this maybe your first go.. I would advice you to follow the water formula first just to get the hang of things.. Once you've acquired a few tumbles under your belt.. you can then decide if you want to try the dry run method.

When its all said and done.. Your looking at about 1 1/2 months to 2 months of maintaining your tumbles., But don't get frustrated or give up. Tumbling isn't easy.. takes time and practice.. most of the time all you need is to make sure the tumblers are quit, run smooth (well oiled) and set in a place where (if any) spills may occur.

I hope this has given you a basic run down of some common issues, corrections and tests you can preform on your stones. As for the "gem" aspect.. Well each stone can be a gem.. But for a true "gem" you'll need to take up the art of lapidary (or cutting stones) then polish them by hand on a combination system (which is a number of belts and disks at veracious grits to achieve a "faceted" gem)

*Hardness.. this is a key factor when tumbling.. You can not simply through any stones of any hardness into any batch.. stones must be organized and separated according to their hardness.. if your unsure what type of stone you have, then you may have an issue with knowing what it's hardness is. Books like: "Handbook Of Rocks, Minerals & Gemstones" is considered to be a good starting reference manual. But of course sites like Mindat.org and others have great images to follow.


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