electrocutus
spending too much on rocks
Member since October 2020
Posts: 331
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Post by electrocutus on Nov 25, 2020 11:38:09 GMT -5
Hi everyone, another newbie question. I searched but didn't see an answer. How close should/must the hardness of different stones be so that I can put them in the same batch in my rotary tumbler? I know the ideal answer is proably that they should all be the same hardness :-)
I have some rough amethyst (mohs 7) and some labradorite (6 - 6.5). I don't have enough of each for dedicated separate batches so I wanted to combine them. Am I asking for trouble? Would I be better to wait until I find/purchase more rocks of similar hardness and then run separate batches, or run 2 separate batches of each rock with lots of ceramic filler?
They are not amazing rough rocks to start with so I don't mind experimenting, but I'd still like to give myself the best chances from the start :-)
I tumble for the fun of getting shiny rocks. I am not planning on making jewelery or anything fancy with the final stones.
Thanks.
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Post by rmf on Nov 25, 2020 15:27:52 GMT -5
The labradorite will grind away noticeably faster than the amethyst. This means the softer will be ready way to move on to the next grit way sooner than the harder. If it were me I would wait until I had enough of either to do a batch. Just as an FYI I have found a Lortone 3A tumbler barrel lets you tumble anethyst and agate together start to polish with no problems. But when you go to a 6# or 12# drum polishing them together results in the amethyst being chipped and frosted around the edges. This is due to the rock falling farther in the tumbler due to increased diameter as well as amethyst being not as tough as agate even though they are the same hardness. So toughness does not equal hardness.
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gatorflash1
spending too much on rocks
Active in Delaware Mineralogical Society, Cabchon Grinding and Polishing, 2 Thumlers B's and a UV-18
Member since October 2018
Posts: 375
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Post by gatorflash1 on Nov 26, 2020 16:00:57 GMT -5
If you check the batch every week and remove those ready for the next step you should be fine. The softer ones will usually finish the stage before the harder ones. They can be mixed together at each stage. I don't mix large hard stones with small softer stones.
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