A mirror is an object with its own identity. Don’t mistake the reflection it makes as the color of the mirror itself. It is just like how an actor can perform on a stage as any number of different characters, but in real life they are still their own unique individual person.
Is Green the Big Surprise?
Your common household mirror will more than likely have a flat, uniform surface. This is most often glass. If so, the glass used is what they call float glass. This type of glass is very common and found in many products other than mirrors such as window panes.
The float glass commonly used when making a mirror is made with soda-lime. This gives the glass a subtle green tint.
To prove that a mirror is green, place two mirrors so that they are in front of each other. That image you see, which looks like it stretches to infinity, is what they call an endless reflection.
If you look closely, you will see that way back in this reflection, where the image turns into a small speck of black, there will be a green color. You are seeing the actual color of the glass at this point. That is why many people will tell you that a mirror is actually green.
Maybe Silver is the Answer?
Maybe you think mirrors are silver. After all, the illustrations of mirrors in the fairytale books are always silver. You may have also noticed that images of mirrors in online and print ads are often silver.
Behind the float glass, mirrors are made with either polished aluminum or silver which is used as the actual reflective surface. Some might even include a coating of mercury in a technique referred to as mercury silvering.
So if you say that a mirror is silver, you are right. Hence, the answer of silver as the color of a mirror is not incorrect.
The Surprising Answer
So what color is a mirror? It is simple. Your basic household mirror that you will find in your bathroom or bedroom is green-tinged glass over a silver reflective surface that mimics the properties of the color white.
Put all of these components together and you have a beautiful and functional mirror that is capable of reflecting all of the colors in the world.