Help ID unusual "seal" mark

I recently acquired this coffee pot. I know nothing about it - guess it to be 18th century, unsure if it is sterling or plated. Instead of impressed marks, it has a raised seal on the bottom with what appears to be an american indian. Is anyone familiar with this? Any info appreciated.


Rainwater, in her Encyclopedia of American Silver Manufacturers, shows this as R Gleason & Sons of Dorchester, Mass and as having been used on plated wares. Gleasons closed in 1871.

Phil