Pleochroism
Definition
The property of some minerals (hornblende, tourmaline, biotite) to show different colours when the plane of polarised light rotates relative to the crystal. Observed with one polar in (plane-polarised light) by rotating the stage.
Related terms
- Birefringence
- The difference between the highest and lowest refractive indices of an anisotropic mineral, seen as a characteristic interference colour between crossed polars....
- Extinction angle
- The angle, measured in degrees on the rotating stage of a petrographic microscope, between a crystallographic reference direction (cleavage trace or crystal...
- Grain mount
- A microscope slide prepared by dispersing sand-grade grains in a mounting medium of known refractive index. Standard forensic grain mounts use Meltmount...
- QEMSCAN / MLA
- Automated mineralogy systems (QEMSCAN is from FEI/Thermo Fisher; MLA is the Mineral Liberation Analyser) that combine a scanning electron microscope with automated...
- SEM-EDX
- Scanning electron microscopy with energy-dispersive X-ray spectroscopy. The electron beam excites characteristic X-rays from each element present in the target grain, giving...
Explained in
- Optical Microscopy and Mineral IdentificationThe property of some minerals (hornblende, tourmaline, biotite) to show different colours when the plane of polarised light rotates relative to the crystal. Ob...