pleochroic


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Related to pleochroic: trichroism

ple·o·chro·mat·ic

(plē'ō-krō-mat'ik),
Relating to pleochromatism.
Synonym(s): pleochroic
Farlex Partner Medical Dictionary © Farlex 2012

pleochroic

(ple?o-kro'ik) [Gr. pleon, more, + chroia, color] Pleochromatic.
Medical Dictionary, © 2009 Farlex and Partners
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Dark green, intensively pleochroic (lightly green-yellowish to dark green or black-green) amphibole grains 0.1-0.6 mm in size have extinction angle [gamma] / c = 13-20[degrees] corresponding to common amphibole.
Rubies, sapphires and green pargasites from Hunza; rubies from Azad Kashmir; pink topaz crystals from Katlang in the Mardan district, North West Frontier Province; emeralds from Swat; peridots from the Sapat Valley in Kohistan; and the remarkable, gemmy and pleochroic lazulite crystals which probably, although not certainly, come from Laila Camp in the Gilgit district ...
In transmitted plane-polarized light, it is strongly pleochroic, orange-red ||[epsilon] and purple-violet ||[omega].
Optical data: Uniaxial (-), indices of refraction could not be measured (material of similar composition has [omega] 1.852, [epsilon] 1.827), pleochroic from orange-brown to yellow.
The crystals are invariably pleochroic, as are all crystals of the minerals of the epidote group.
It is pleochroic with a glassy luster, has no cleavage, a hardness of just over 2.0 and a specific gravity of 3.35 (Palache, 1937; Ahlfeld and Munoz Reyes, 1955).
The mineral is pleochroic; translucent (masses) to transparent (crystals); very pale blue to blue-gray (crystals) or blue (masses); with a white streak and a vitreous to glassy luster.
Optical data: In reflected light: pink with a lilac tinge, distinct to moderate anisotropism, weak to distinct bireflectance, pleochroic from brownish pink to pinkish lilac.
Optical data: In reflected light: gray, strong anisotropism, strong bireflectance, pleochroic in gray colors.
It is biaxial with an indeterminate optic sign and [alpha] 1.667(1), [beta] 1.679(1), [gamma] 1.690(1), 2V(obs) = 89(2)[degrees], 2V(calc) = 87(5)[degrees], strongly pleochroic with X = yellow-brown, Z = dark yellow-brown, Z > X, X [conjunction] b = 20[degrees] (in [gamma] obtuse), Y [conjunction] C = 13[degrees] (in [alpha] acute), Z = a.
Optical data: in reflected light: white, distinct anisotropism, perceptible bireflectance in air (a little more in oil), slightly pleochroic in grayish white and creamy white.
The optical orientation is X = c, Y = b, Z = a, and the mineral is pleochroic with X = yellow, Y = brown, and Z = light green.