spring hinge...
mcmaster-carr.com and many hardware stores carry the type with the leaf spring; which can be reversed to automatically open instead of automatically close, so that it may befit your design. How will you tolerate the thickness of the glass and the placement of the hinge? You would probably need to build up the contacting "flap" with an angle, in such a manner that the hinge does not "close" all the way down, but the flap does.