Mercury, Tin Silvered Mirrors

[ady]

I have an old oak framed mirror. The weight is very deceptively heavy and me think if it was silver backed as has a few tell tale signs from marks appearing on the front. I have not removed the back and appreciate a filler might be there, and the glass is very thick. I am under no elusion of having vast ounces of silver! All this said does anyone know what quantities of silver were used in old mirroring?

[Murph]

Not a lot.  
Given how easily damaged mirrors are and that’s through the slivering and a protective paint layer.

I think you’d probably find the silver is as thin or thinner than silver plated cutlery.