Tenebrescent tugtupite: normally pink, it changes color to a darker red upon exposure to UV light. Strong white light reverses the color back to pink. The fluorescence under UV light is typical for tugtupite: bright red and orange under short and long wave, respectively. More interestingly, it fluoresces a nice pink under midwave UV and shows a very long lasting white afterglow after exposure to UV light (any of them).
Fluorescence under shortwave UV light.
Fluorescence under longwave UV light.
Tenebrescence (reversible photochromism) after exposure to UV light.
Normal light.
