Smoke blackening sterling

Had an interesting reaction with a sterling silver chain last
weekend. I was out at our farm smoking some sausages in our home
made smoker. I live in Venezuela and it was an exceptionally hot day
so I was working up a pretty good sweat as well as being exposed to
thick clouds of wood smoke every time I opened the smoker door. When
I went inside to clean up, I was surprised to see that the sterling
silver chain that I was wearing had turned black. It was a bugger to
clean and I eventually had to re-polish and re-tumble to remove the
black tarnish. I assume there were some sulfurous elements in the
woodsmoke, which when combined with the salts in my sweat reacted
with either the silver or the copper to form the tarnish. I’m
curious if any else has experienced this type of thing or can shed
light on the reaction

John Bowling