In 1948, Hodgkin first encountered ring structure because the crystals were pleochroic, a finding which she later confirmed using X-ray crystallography.
12.
The commercial title of " dichroic " can also display three or more colors ( trichroic or pleochroic ) and even iridescence in some cases.
13.
It is also used in some pleochroic dyes and together with e . g . cholesteryl oleyl carbonate and cholesteryl benzoate in some thermochromic applications.
14.
The mineral is pleochroic; when viewed along the X direction it appears pale green, and bluish green along the Y and Z directions.
15.
Alexandrite, a strongly pleochroic ( trichroic ) gem, will exhibit emerald green, red and orange-yellow colors depending on viewing direction in partially polarised light.
16.
Tourmaline hornfels are found sometimes near the margins of tourmaline granites; they are black with small needles of schorl that under the microscope are dark brown and richly pleochroic.
17.
Pleochroism is often especially intense in small spots which surround minute enclosures of other minerals, such as zircon and epidote, these are known as " pleochroic halos ."
18.
The 2H polytype is pleochroic, meaning that the mineral changes colors ( in this case yellow and light yellow ) when viewed at different angles under a polarizing petrographic microscope.
19.
Mindat . org stated that the mineral gabrielite is not pleochroic ( different wavelengths are absorbed in different directions, the color of the mineral varies when rotating the stage in plane polarized light ).
20.
In the latter case, the decay of a radioactive element damages the mineral crystal; the result, termed a " radioactive halo " or " pleochroic halo ", is observable by various techniques, such as thin-section petrography.
