I have a 1965 quarter there is no mint mark. The fact that I can see more copper on the back then silver and the ridges on the side are on the back. you can make out united states of america on top of back and quarter doller on bottom of back in the ridges the eagle is fully visable. Not sure of weight but the thickness is that of a dime anyone seen anything like this before? Wish I could provide a better picture.