Henry
spending too much on rocks
Member since January 2013
Posts: 452
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Post by Henry on May 9, 2015 11:17:37 GMT -5
Hello all. I recently found a dealer that sells agatized dino. bone at a reasonable price. My quandary is this: so I guess the "norm" is to slab and cab the stuff. Would it be out of the question to attempt to tumble these pieces...or would the matrix be so inconsistent that you wouldn't get a good polish would it crumble on you. Please forgive me because I am absolutely oblivious to this area. Henry
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Fossilman
Cave Dweller
Member since January 2009
Posts: 20,681
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Post by Fossilman on May 9, 2015 13:17:56 GMT -5
I suppose you could tumble them-but most people do it all with wheeled polishers...With the belts or wheels you can spot,if its doing damage and stop-with a tumbler you can't.. An expensive "Boo Boo"!
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Post by Peruano on May 9, 2015 13:31:56 GMT -5
I agree with fossilman's assessment. Reptile bone is extremely variable in its porosity in life, and presumably a lot of that variation will be reflected as its fossilized as well (or at least could and that's the unknown referred to above). What happens is as the bone grows from tiny to bigger (sometimes huge), it is constantly reorganized with calcium removed from the center and redeposited peripherally where the bone is growing (breadth as well as length), so the absolute center may be an open hole (filled with marrow or fat), or a very flimsy honeycomb of light vacuoles and intervening partitions. Further out it will be smaller vacuoles, more calcium, heavier partitions, and stronger. Thus every cut could be slightly different, and as you move from the center of the bone to the perimeter, the structure and density is likely to change. Often the dino bone fragments found as fossils are densest parts that have survived the best - the fragile parts are gone to weather, river action, and just the passage of time, and chemical dissolution. Me, I'd cab them unless I had some surplus that I just wanted to experiment with, but success on one will not necessarily mean you know what will happen with a different specimen. Good luck. This is coming from a person who tried to age turtles by making thin sections of bones with a diamond saw, back in a life before rocks (LBR). Tom
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Sabre52
Cave Dweller
Me and my gal, Rosie
Member since August 2005
Posts: 20,456
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Post by Sabre52 on May 9, 2015 20:42:03 GMT -5
Yep, what Tom said. I've experimented with tumbling dino bone and it's very hit or miss. Often the walls of the cells seem to be composed of minerals less hard than the silica fillings of the cells. The result is in some instances, serious undercutting of the cell walls. In other instances the interior of the cells can be pitted as the centers of the cells seem to be softer. In ideal instances, the whole specimen is well replaced with silica and tumbles up just fine but that has not been a common experience for me. Way better to do bone on the wheels..Mel
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Post by glennz01 on May 10, 2015 10:28:55 GMT -5
Yep, what Tom said. I've experimented with tumbling dino bone and it's very hit or miss. Often the walls of the cells seem to be composed of minerals less hard than the silica fillings of the cells. The result is in some instances, serious undercutting of the cell walls. In other instances the interior of the cells can be pitted as the centers of the cells seem to be softer. In ideal instances, the whole specimen is well replaced with silica and tumbles up just fine but that has not been a common experience for me. Way better to do bone on the wheels..Mel I tumbled some scraps I had a while ago... Turned out nice for me... the cell walls gave undercutting but I liked that texture. If you didn't pay much and don't have a cabbing machine i'd probably tumble them... or wait until you can cab them... but your small thick one should be fine to tumble. I only have the stones in the tumbler for 4-6 weeks... only 1 or 2 weeks on the rough tumble to round it out... I don't take all the flaws out so if you tumble for 2+ months than i'm not sure about tumbling.
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Henry
spending too much on rocks
Member since January 2013
Posts: 452
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Post by Henry on May 10, 2015 21:26:37 GMT -5
Glenn you must be talking about the small thick one with purple-ish cells? That's the one I wanted to tumble. The other two, I want to make them future projects for a cabbing machine...when I get one. Um, stupid question: what's "undercutting"?
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Post by glennz01 on May 10, 2015 22:47:30 GMT -5
Glenn you must be talking about the small thick one with purple-ish cells? That's the one I wanted to tumble. The other two, I want to make them future projects for a cabbing machine...when I get one. Um, stupid question: what's "undercutting"? yep. Undercutting is when the softer material erodes away before the harder material, sometimes it can erode under the harder material like a river does.. but this is uncommon. I don't have a photo to show unforunitally
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Fossilman
Cave Dweller
Member since January 2009
Posts: 20,681
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Post by Fossilman on May 23, 2015 14:53:13 GMT -5
I have some prehistoric bones(not dino) that I have in the tumbler now...These,I could care less if they get ruined,very common bone from the Ice-Age! Did a grit change on the batch a few days ago-they are doing nicely...No undercutting-solid through out...
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