Imitation d'inclusion par gravure laser dans un quartz naturel

This article describes a small near-colorless quartz (rock crystal) sphere containing four remarkable white inclusions with a radial structure, in the shape of spherical tassels. It was acquired on a internet sales platform. The experiments were able to highlight the natural character of this quartz because it contains two-phase fluid inclusions, and shows infrared absorptions at around 3595, 3482 and 3378 cm-1 typical of natural quartz. The white inclusions were obtained by bursting caused by computer-controlled 3D laser “etching” to form remarkable patterns, and this, before purchase. Defects resulting from the same process have already been observed in natural quartz. However, here we describe for the first time the short ultraviolet only blue luminescence of these inclusions. By luminescence spectrometry, it has been established that the blue fluorescence is due to missing oxygen atoms caused by laser irradiation, and which have probably moved into nearby interstitial sites. An orange emission, not visible to the naked eye, is linked to this presence of interstitial oxygen.