Video Showing Tenebrescence in Scapolite from Afghanistan

Tenebrescence refers to a reversible color change in which a mineral darkens in response to radiation of one wavelength and lightens on exposure to a different wavelength. In this video, three tenebrescent scapolites from Afghanistan (up to 5.17 ct) are first shown under a strong UV source, which causes their blue coloration. When the UV source is switched off and the stones are exposed to a strong incandescent light source, the blue color fades completely within approximately 25 seconds. Stones courtesy of H. Obodda; filmed by Pedro Padua.