The color shown in the mirror tunnel (due to specular reflection) can depend upon three things: 1. The material used as the reflective coating (silver, chrome, copper, gold, mercury, aluminum, and other oxides). The most commonly used modern coating is aluminum. In regular sunlight,asilver or aluminum coating could show anything from green toagreenish-blue. Copper could beagreenish-orange. Gold could be greenish-yellow. 2. The type of light being reflected (due to metamerism). Ifamercury-vapor light, orasodium-vapor lamp were used, different colors would be reflected. Although the above two items can cause some color discrepencies, the 3rd reason is what will normally be perceived… 3. The composition of the glass. The most commonly used glass is soda-lime glass. Ordinary soda-lime glass appears colorless to the naked eye when it is thin, although iron oxide (FeO) impurities of up to 0.1 wt% produceagreen tint.