Photomicrography > Quartz > with phantoms
First draft: April 19th, 2016 | Last update: April 19th, 2016
Almost all deposits
Phantoms are quite common in quartz crystals as they are the result of changes taking place during the growth process. Analoguous phenomena also occur in other minerals - colour zoning in corundum being one example. As long as no changes take place in the growth environment of a crystal, the crystal will continue to grow unaltered.
However, any change in temperature, pressure, composition of the surrounding fluid from which the crystal gets its nutrients, like depletion of a chromophore, results in colour zoning. Depletion of a compound may terminate growth and trigger etching or partial dissolution or deposition of a different mineral or phase.
Quartz may contain all of the above as is illustrated by the wonderful crystals from Goboboseb, Namibia. Nevertheless, whatever the nature of the phase deposited, sudden changes in the growth environment so to speak document earlier versions of the crystal as is observed in these examples.
Legend: FoV: Field-of-View; DoF: Total focusing depth; DF: darkfield; Obl: oblique illumination (fiber optics); Pol: polarising filter before objective; Sh: shadowing; TM: transmitted illumination, UVL: long-wave ultra-violet radiation; UVS: short-wave ultra-violet radiation; X-Pol: crossed polarising filters