...Lætitia Gilles-Guéry; Laurence Galoisy; Jurgen Schnellrath; Benoit Baptiste; Georges Calas Abstract Pink euclase of gem quality and centimeter size, presenting an unusual pink-orange coloration and a pink to orange pleochroism, was discovered near Livramento de Nossa Senhora, in Bahia State, Brazil...

.... It is transparent, green, with vitreous lustre. The calculated density ( D calc ) is 3.844 g cm −3 . Elasmochloite is optically uniaxial or pseudo-unixial (−), α = 1.611(2), β = γ = 1.698(2), 2 V ≈ 0°. Pleochroism is strong, Z ≈ Y (grass-green) > X (turquoise-blue). The chemical composition obtained by electron...

... microscopy (TEM), and its mineral chemistry has been investigated by means of wavelength-dispersive and TEM-based energy-dispersive spectrometry. In thin section, Fe-rich antigorite is characterized by a strong, peculiar pleochroism (α = green–dark green; γ = bright-yellow–orange). It occurs in both mesh...

... > v . The optical orientation is X = c , Y = a , Z = b . The pleochroism is X = yellow brown, Y = olive brown, Z = dark olive green; Z > Y > X . Crystal structure refinements on ferrirockbridgeite and other oxidized rockbridgeite-group species, including type rockbridgeite and type frondelite...

... = 1.781(calc), γ = 1.797(3) (white light) and 2 V (meas.) = 87(1)° from extinction data. The optical orientation is X = c , Y = a , Z = b . The pleochroism is X = blue green, Y = olive green, Z = yellow brown; X ≈ Y > Z . Corresponding author, e-mail: Ian.grey@csiro.au 21 08 2018 17 10...

... cleavage parallel to {001} and Mohs’ hardness of about 4. The measured density is 2.89(2) g cm −3 . Optically, it is biaxial (+), with α = 1.655(2), β = 1.662(2), γ = 1.673(2) (white light); 2 V = 78(1)°; pleochroism: X nearly colourless, Y and Z beige; X < Y ≈ Z . Electron microprobe analyses gave...

..., the mineral dissolves rapidly in dilute HCl. Optically, manganflurlite is biaxial (–), with α = 1.623(calc), β = 1.649(2), γ = 1.673(2) (white light); 2 V = 86(1)°. The dispersion is r > v , slight; the optical orientation is X = c , Y = b , Z = a . The pleochroism is X = pale yellow brown, Y = orange...

... (+) and has a 2 V angle of ≅ 70° with strong dispersion. It exhibits weak to moderate pleochroism: orangish-yellow parallel to cleavage and greenish-yellow perpendicular to cleavage on (010). The measured Z ∧ c is 5–12°. The birefringence is strong to extreme; interference colors are very high-order tints...

..., meitnerite is biaxial (–), with α = 1.568(2), β = 1.589(2), γ = 1.607(2) (white light); 2 V = 84(1)°. The dispersion is r > v , moderate, The optical orientation is X ∧ b = 26°, Y ∧ a = 15°, Z ∧ c = 53°. The pleochroism is X nearly colourless, Z pale green yellow, Y light green yellow; X < Z < Y...

...: perfect on {001} and good on {100}. The measured density is 2.85(2) g/cm 3 . Pararaisaite is biaxial (+) with α = 1.600(2), β = 1.616(2), γ = 1.713(3) (white light); 2 V = 47(1)°; slight r > v dispersion; orientation Z = b , X ≈ a , Y ≈ c ; and pleochroism X very pale purple, Y purple, Z blue green ( X...

... is ∼5. The calculated density is 3.613 g/cm 3 (for empirical formula). Optically, it is biaxial positive, with α = 1.674(2); β = 1.692(3) and γ = 1.730(3); 2 V γ is very large, ∼75° (est.), 2 V γ (calc.) = 70°. Pleochroism is moderate: X (pale) blue, Y pale blue and Z pale blue with faint greenish tint...

...°. Dispersion is moderate, r < v . Pleochroism is X = very pale yellow green, Y = pale yellow green and Z = light yellow green; X < Y < Z . The optical orientation is X ≈ c , Y ≈ a and Z ≈ b* . The Raman spectrum exhibits bands attributable to both sulfate and uranyl groups. Electron probe...

... density is 6.324 g cm –3 . In reflected light bytízite is grey with a yellowish hue, yellowish and brownish. Bireflectance and pleochroism are weak. Anisotropy is strong with grey to brownish rotation tints. Internal reflections were not observed. The empirical formula, based on electron-microprobe...

... color in red core and green board are microplates of native Cu. Figure 2. Transmitted light photomicrographs of a polished sunstone crystal (~5 mm thickness) from the green border part show pleochroism (light brown to pale green). The cleavage plane (001) is perpendicular to the light. Some...

...Ziyin Sun; Aaron C. Palke; Jonathan Muyal; Robison Mcmurtry Abstract Pleochroism plays an important role in determining the face-up visual color appearance of faceted, optically anisotropic (non-cubic) gemstones. One area that has received little attention is the interplay between pleochroism...

... and ∼3335 cm −1 with contrasting bandwidths of ∼40 and ∼90 cm −1 , respectively. The two OH bands show strong pleochroism and dominant infrared absorption in the Y direction. The IR spectra of natural monazite contain a weak pleochroic OH band centred around 3400 cm −1 with a bandwidth of more than 200 cm...

..., juansilvaite is biaxial (+) with α = 1.575(1), β = 1.597(1), γ = 1.623(1) and 2V = 86(1)° (measured in white light). Dispersion is r < v , slight, and the orientation is X = b ; Z ^ c = 27° in the obtuse angle β. The pleochroism is X > Y ≈ Z in shades of pale pink. The mineral is slowly soluble in dilute...

... with a lilac hue and vitreous lustre. Dominant crystal forms are {1 0 0}, {1 1 0} and {3 3 1}. The Mohs hardness is 6.5. D meas and D calc are 3.40(3) and 3.41 g/cm 3 , respectively. Cyprine is optically uniaxial, negative, ω = 1.744(2), ε= 1.732(2) (in white light). Pleochroism is strong; ranging from O...