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Unseen Concussion Damage


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A lot of times you look at the surface of a marble and you see the obvious chips, scuffs, and other damage, but beneath the surface their may be a lot of unseen damage. This damage is usually not obvious to the naked eye when one is casually observing the marble. It is consussion damage. Damage that is transferred internally into the marble but did not do damage to the marbles exterior surface. I did a Sulphide once that only had a couple of small chips and scratches but the owner of the marble wanted the small chips removed along with the scratches. When the machine broke through the annealing hard highly polished surface it exposed hundreds and hundreds of concussion hits and all af them had left their perfect little ring damage internally in the marble. Ronnie



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On the one side only is odd indeed. So, to clarify, this is not one you've polished yet.

My guess is some sort of calcium or lime build up. Check valve?

No it has not been ground, (3 stage fining, yes 3 stages) and then "POLISHED". The marble had the concussion damage on it's entirety. What happened was it had a substantial chip near the equator and I knew if I tried grinding out that chip it would have opened up the pontils big time. So I decided to hand work that large chip area. So you start at the perimeter of the chip and hand grind away from the chip (work outward 360 degrees) feathering the pressure (lighter pressure as you move away) ( the depth of the chip determines how far you move away from the epicenter) So what you're seeing in the photo is where the feathering stops. Doesn't matter though I still succeeded in screwing up the marble as I opened up the pontils (a small amount but still opened up) and to me that ruined the marble. Ronnie
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