Molybdenite. Jersey, Channel Islands, Britain
Coarse blades and laths of molybdenite show strong bireflectance and reflection pleochroism. The strong basal cleavage of molybdenite (left) parallel to (0001) is clearly seen, as are deformation effects similar to kink banding (centre). The dark grey area (bottom) is quartz. Four trigonal carbonate crystals showing bireflectance are lighter grey (bottom left). Black areas are polishing pits.
Polished block, plane polarized light, x 40, air