Blue phosphor is one of the three common phosphors. It has moderate energy levels and can exist in both mineral and organic forms. Its mineral form can be found in the Barrens' metallic sands, while the organic form can be found in phosphor shrimp and their secretions (see below). The light emission of blue phosphor is powerful, but it has a "self-conserving" property. If it is left alone for a period of time, it will stop glowing. Agitation of the blue phosphor restores its glow.
Also known as "seed shrimps," these are the most abundant life form in the oceans surrounding the Barrens. They consume toxic gases that gas vents around the Barrens produce and are responsible for keeping said toxic gases from drifting to the Glen. During their spawning period, they produce a rare form of blue phosphor. When combined with the toxic gases, this phosphor produce an acidic solution primarily used to clean the rust off of robots.
Green phosphor is one of the three common phosphors. It has the highest energy levels of the three, and is also the rarest of the common phosphors, existing exclusively in organic forms. It can be found in the sap of phosphor trees, fireflies, and various mosses. It is ideal for industrial use but due to its scarcity compared to the other three, there is no reliable source.
The trees are special as they grow without any leaves and function similarly to blades of grass. They have circular holes in them containing their green phosphor sap. According to some robots in the Glen, harvesting the trees is no longer allowed.
Common fireflies, nocturnal beetles that glow vibrantly, have an abdominal phosphor organ which allows them to glow green during the night. The locals of the glen would capture them en masse and use them as living lamps.
Red phosphor is one of the three common phosphors. It has the lowest energy levels and exists exclusively in mineral form. It only produces light when in solution. Red phosphor present in the Refuge's water channels can be concentrated and using presumably electric "currents," a high-energy state with greater luminosity can be induced. This supersaturated solution precipitates out rather quickly. Once the phosphor re-crystallizes, it loses its glow permanently. If the supersaturated red phosphor is used as a power source, proper facilities or services should be present to replace it frequently. According to the lamplighter, an army of robots used to do this but they started breaking down, leaving him to do their job.
Yellow phosphor is special in that it glows forever and is the same phosphor that fuels the Sun. Three pieces of it, and help from the Player, are also required in order to enter into the Tower. It is theorized that yellow phosphor isn't affected by resets in the game, as Rue (yellow phosphor on her forehead), Niko (in Niko's yellow eyes), the countdown in the office (yellow in color), and multiple other instances containing yellow phosphor recall the Player and some of their actions throughout the game.