Tenebrescence

Tenebrescence, also known as reversible photochromism, is the ability of minerals to change colour when exposed to sunlight. The effect can be repeated indefinitely, but is destroyed by heating.

Additional recommended knowledge

Daily Sensitivity Test

Recognize and detect the effects of electrostatic charges on your balance

Daily Visual Balance Check

Tenebrescent minerals include hackmanite sodalite, spodumene and tugtupite.

Tenebrescent behavior is exploited in synthetic materials for the manufacture of self-adjusting sunglasses, which darken on exposure to sunlight.