Dichroism

[From Gr. dichroōs, bi-colored.] ( Min.) A term applied to those minerals which present different colors, when viewed by transmitted light, in two different directions; the colors being the same in the direction of like axes, and different in that of unlike axes. Iolite is an example of this property, and the name Dichroite has been given to it in consequence. Mica affords another instance, being nearly opaque when viewed in one direction, but transparent and of a different color in another. A good instance of D. occurs in the crystals of chloride of palladium, which appear of a deep red color along the axis, and of a vivid green when viewed in a transverse direction.