Did i get burned?

[Detroit_Refined]

I bought a few lots of scrap sterling to use for inquartations in gold refining. As i was melting one of the spoons, the flame went from green to blue to white. Im starting to wonder if I might've had a spoon that contained zinc or possibly a silver plated zinc spoon. Anyone else run into this problem when melting silver?

The inquartation and refining process did not go well. Everything was fine at first but when i did the 2nd nitric addition in aqua regia, the solution became cloudy and nasty looking. A greyish blue mud formed and slowed my filtering process way down. The rinse water stayed filthy and this mystery precipitate is following the gold

Im about a gram and a half shy of my expected yield, could use some advice. Thx.

 

[Refining Rick]

I suspect it is tin, and it made metastannic acid.

 

[FrugalRefiner]

From the sound of the "greyish blue mud formed and slowed my filtering process way down", I tend to agree with Rick.

Were all the pieces stamped sterling? If not, never mix crap with your scrap. It just causes problems down the line.

Dave