The color of a mirror is a bit of a tricky question. Most mirrors are technically white with a slight green tinge because of their underlying layer of silica glass. However, a mirror is not silver or grey. The color of a mirror is actually the color of whatever is reflected onto it. A perfect mirror has specular reflection, meaning it reflects all light in a single direction equal to what it receives. Specular reflection creates an image of whatever object is in front of it. But most mirrors we use arent perfect, and their surface atoms give any reflection a very slight green tinge, as the atoms in the glass reflect back green light more strongly than any other color. So, in simple terms, a mirror is whatever color its reflecting at the moment.