Definition of pleochroic in US English:



  • (of a crystal) absorbing different wavelengths of light differently depending on the direction of incidence of the rays or their plane of polarization, often resulting in the appearance of different colors according to the direction of view.

    • ‘Augite is generally complexly zoned and pleochroic and has Ti-rich rims.’
    • ‘It generally occurs as euhedral-subhedral hexagonal books, which commonly display a mottled green-brown pleochroic appearance.’
    • ‘The crystals lacked the characteristic pleochroic color scheme of piemontite.’
    • ‘Crystals are strongly pleochroic, resulting in distinctly different colors when viewed in different optic directions.’
    • ‘In this book Joly also discussed the measurement of the radioactivity of rocks and the origin of pleochroic haloes.’


Mid 19th century: from pleo- ‘more’ + khrōs ‘color’ + -ic.