A vocabulary of landscape — a landscape of words
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tyndall blue
Tyndall blue is blue produced by scattering rather than by pigment. There is no blue pigment in a blue jay’s feather, a blue eye, a blue-skinned monkey’s face, or most blue butterfly wings; the color comes from microscopic structure that scatters short wavelengths back at the eye while a dark backing absorbs the rest. Crush the structure and the blue vanishes, which is the simplest way to prove what is happening.
Etymology
The effect is named for John Tyndall, the Irish physicist who investigated the scattering of light by fine particles in the 1860s and demonstrated that it explained the color of the sky. Lord Rayleigh worked out the mathematics shortly afterward, and Rayleigh scattering covers the molecular version, with Tyndall’s name attached to scattering by larger particles and structures.
Notes
Blue is the rarest pigment in nature and the commonest structural color, and that is not a coincidence. Producing a true blue pigment is chemically difficult, and building a structure that scatters blue is not. A blue feather ground to powder is brown, a green frog is a blue structure under a yellow pigment, and grinding a green parrot feather produces yellow dust.