Smoky Quartz

Light to dark brown quartz crystals are called smoky quartz. Very dark brown, almost black quartz crystals are called morion. The colour was produced by ionising radiation from the surrounding rock. For this, however, the quartz must have potential colour centres, which consist of lattice defects. It is quite possible that clear rock crystals as well as smoky quartz can be found in the same pocket.

By heating smoky quartz above 200 ºC, the colouration can be reversed. This is rarely done. The reverse, i.e. making light quartz darker by artificially irradiating it, is a con that one encounters from time to time.

Photo: Quartz (smoky quartz), Galenstock VS, Felix Spahr collection; not for sale.