Roman/Greek Plate or Plaque

Hi,

Won this as part of a lot at auction and I would consider this as a decorative plate or plaque and tested using strong magnet so either copper or bronze.  I'm not sure is copper and bronze tarnish/tone the same?  Item weighs approximately 3 pounds and is 8.5" in diameter.  By the marks on the back of plate, I'm guessing it was cast and also on the back is 1841 so my guess is it is from the year 1841. The engraving of 1841 appears to be hand stamped but again, unknown.  I searched many hours online and found nothing but on ebay, there are plaster wall plaques with the indentical scene of what I would call roman or greek harvest scene.  Any help in determining what this actually is called, along with the scene, if the age if correct and possible value range, would be very much appreciated.

Fair