Difference between crystal and pleochroism
- glassware made of quartz
- a solid formed by the solidification of a chemical and having a highly regular atomic structure
- a protective cover that protects the face of a watch
- colorless glass made of almost pure silica
- a crystalline element used as a component in various electronic devices
Save for a worktable placed almost exactly in the center of the floor, I see only a few benches, some unlit rush lamps, a large set of scales, and a wooden crate, which I discover upon examination contains small crystal vials waiting to be filled.
Clearly the megalosaurus in the opening passage of Bleak House is a flight of hyperbolic fancy (inspired, I would guess, by the papier-mâché dinosaurs constructed for the Crystal Palace Exhibition, a couple of years earlier).
Cppd crystals are smaller rods, squares, or rhomboids and are difficult to identify with light microscopy.
- the phenomenon of different colors appearing when certain crystals are viewed from different directions
This colour variation is pleochroism (strictly trichroism in biaxial minerals).
Iceland-spar is extensively used in the construction of Nicol's prisms for polariscopes, polarizing microscopes and saccharimeters, and of dichroscopes for testing the pleochroism of gem-stones.
Optically, purple apatite commonly shows slight bluish to reddish pleochroism.