Polylucent cuprothallium is a transparent material used in heads up displays and communications devices used for projecting data.
Cupro is a cellulose based fiber or fabric. Polylucent cuprothallium is cellulose doped with thallium (which is used in optics and electronics), used to make 3D displays.
It is a manufactured substance based around a copper-thallium alloy that emits low levels of EM energy across a broad spectrum when a power source is applied to it. The substance is inherently unstable. It is typically found as a molecular layer within a transparent veneer, such as a vacc suit visor, where it can be electrically induced to display data.