Hornblende (48%) forms heteroblastic and subidioblastic individuals, strongly fractured, of tabular-prismatic shape with intense pleochroism
varying shades of green to brown.
Hornblende shows yellowish green to green and lamprobolite light brown to reddish brown pleochroism
, whereas both displays well developed sets of 56deg and 124deg cleavages in basal sections.
7-1 Fiber Manipulations: Removing Fibers from Tape and Mounting 7-2 Observing Effects of Mounting Media 7-3 Observing Fiber Shape, Surface and Internal Structure 7-4 Observing Color and Pleochroism
7-5 Distinguishing Natural and Manufactured Fiber Classes
A grain mount, with a Na-gel filtered light (590 nm), shows that lafossaite is yellow-brown in plane-polarized transmitted light, isotropic, and displays no pleochroism
O = bluish with a grayish tint, E = pale bluish with a grayish tint, O [greater than or equal to] E.
strong, O = pale yellow, E = yellowish orange.
638, 2V could not be measured but must be very small, dispersion could not be measured; pleochroism
medium strong, X very pale bluish, Y and Z bluish with a greenish tint, Z [approximately equal to] Y [much greater than] X; orientation not given.
Optical data: In reflected light: pink sometimes with a slight grayish tint, weak anisotropism from light gray to brownish gray, no bireflectance, pleochroism
52[degrees]; dispersion not mentioned; pleochroism
distinct, X = very pale blue, Z = pale greenish blue; X ^ a = 22[degrees] in obtuse angle [beta], Y [approximately equal to] c, Z = b.
70[degrees], dispersion not determined; pleochroism
strong, X = light brown, Y = red-brown, Z = yellow; X ^ c = 15[degrees] in acute angle [beta], Y = b, Z ^ a = 40[degrees] in obtuse angle [beta].
is usually distinct, from medium blue to pale greenish blue.
50[degrees]; dispersion not given; strong pleochroism
X = violet-red, Y = green, Z = greenish blue; Z = b, X^c = 23[degrees] (in obt use angle [beta]), Z^c = 5[degrees] (in obtuse angle [beta]).