...Matthew J. Kohn Abstract Mineral separates mounted in thin section help introduce mineralogy students to concepts of relief, color, pleochroism, and birefringence and serve as reference materials both for research and teaching. Here, a simple method is described to produce materials that can...

... density is 2.654 g·cm -3 . The Raman spectrum contains the following bands: 379, 357, 289, 236, 167, 131 and 124 cm -1 . In reflected light, the mineral has very strong pleochroism from yellow-pink to dark-grey. Anisotropy is very strong, ∆ R 589 = 69 %. Reflectance values for COM required wavelengths...

...) (white light), and 2 V (calculated) = 83°. The dispersion is medium with r < v, and the pleochroism is with X = light brown, Y = brown, Z = dark brown. The color, streak, luster, and hardness (Mohs) are light brown, yellowish gray, vitreous, and 4½–5, respectively. Jingwenite-(Y) is monoclinic...

...-bearing plagioclase, as a function of particle size and shape, is also calculated from the computed extinction spectra. The colors and pleochroism observed in natural and treated Cu-bearing plagioclase can be explained from the computational results. The enigmatic green colors in some precious Oregon...

...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...

... grains show strong pleochroism from light greenish yellow to dark greenish brown and are highly fractured ( Fig. 3d ). Fig. 3. Petrography of pegmatite shows (a) Plagioclase grain showing zoning; (b) Granophyric texture at contact between perthetic Kfeldspar, plagioclase and quartz; (c...

.... 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 . 21 08 2018 17 10 2018 18 10 2018 © 2018 E...

... 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...