Chemical reaction?

[Citizen H]

Victorian 1879 3d

I always soak new addition grimy silver coins in warm soapy water and a gentle tooth brush then rise.... just enough to remove hand grease and grime and wait to see what the coins turn out to be condition wise.

on this occasion I haven't come across this before... it looks like in its life it may came into contact to maybe an acid,? its not pitting?? so is it Erosive or Corrosive reaction?

any explanations from mint issues ? cheers "H"     

[VickySilver]

Ground find/detector?  Sometimes there can be moist soil contact with bits or grains of acidic components, not a solution - if that makes sense..

[Citizen H]

1 hour ago, VickySilver said:

Ground find/detector?  Sometimes there can be moist soil contact with bits or grains of acidic components, not a solution - if that makes sense..

you know you could be right, the coin although the faults it has doesn't have much signs of circulation wear, and buried in acidic soil makes sense, I cleaned of the crud & grime ....Many thanks "H"