Juillee here is a pic of the dark tower at the top is the mirror which gives the light that shines from Mordor.
I hope there is a light in Mordor but it has been about twenty years since I read lord of the rings. My memory is an image of a dark mountain with an evil light coming from it a red light maybe. Maybe the Nazguls are vain and like to look at themselves in the mirror
In real life the mirror is golden in color and quite striking and beautiful at times