A mirror might look silver because that is the usual depiction in books or movies, but it is actually the color of whatever is reflected onto it. Glass mirrors are typically coated with non-toxic silver or aluminum, both of which are grayish or silvery.
Glass is green, but only when it's really thick, like when you try looking thru a mirror edgewise. A mirror is clear glass with a metallic coating on the back side. The coating is usually silver, which is a light grey color. Silver is not a color, its a description of shininess.
Actually in reality we won't have mirrors . We just a choose convenient type of transparent glass and paint the backside of the glass with silver clour to make it opaque . Instead of silver colour u can use anyother colour too. But silver colour is the most suitable colour and most popularliy used colour.