What happened here!?

[goldenchild]

Ok. I had a twice refined ingot that I decided to use as a time saver(I know i probably shouldnt have done that) because it was only 22.8 grams and I sell by the ounce.



I was doing the first AR digestion on some gold filled jewelry foils and put the ingot in to exhaust any free nitric. There wasnt much of a reaction but I boiled and followed normal procedure. When I filtered the solution and the ingot dropped out boy was I surprised. After rinsing it off this is what I got.





Looks like white gold or a charm that was gold over silver plated. The ingot now weights 22.5 grams. I have processed pounds and pounds pause... and pounds of gold filled material and this has never happened. Any ideas? Not a big deal but I thought I would share this with you guys.

 

[lazersteve]

Maybe the bar contains some surface base metal impurities that cemented a touch of silver out of the solution as a thin layer. Perhaps these impurities made it to the surface of the bar from your torch tip as vaporized metals?

If you boil the bar in nitric acid does the silver lining go away?

Steve

 

[samuel-a]

Maybe the bar contains some surface base metal impurities that cemented a touch of silver out of the solution as a thin layer. Perhaps these impurities made it to the surface of the bar from your torch tip as vaporized metals?

If you boil the bar in nitric acid does the silver lining go away?

Steve

good thinking steve

my first hunch was Pt that cemented on the gold.. but i probably wrong...

 

[goldenchild]

I used a brand new torch to melt this ingot so I dont know if it was contamination from the torch. I recently sold some ingots that I used the same procedures(as I always do) to process and they were assayed at 24k. After posting the pictures I took a couple of drops of 70% nitric and dropped them on the ingot. The ingot instantly turned back golden as the day it was born so it seems the material was right at the surface. I wonder if there was somehow so much copper in the digestion that it plated some silver onto the ingot? Again there was not much reaction when I put the ingot into the AR.