Blue Inclusion in Rock Crystal Quartz

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This 118.16 ct polished modified cube of rock crystal quartz contains an interesting tuft of blue needles, which may be tourmaline.

Figure 1. This 118.16 ct polished modified cube of rock crystal quartz contains an interesting tuft of blue needles, which may be tourmaline. Photo by Robert Weldon; courtesy of Mike Bowers.

Tuft of blue needles in rock crystal quartz.
Figure 2. This tuft of blue needles has nucleated on a quartz crystal and tapers toward the end opposite the core quartz crystal. Although too deep to be identified by Raman spectroscopy, the needles resemble light blue needles of tourmaline. Photomicrograph by Nathan Renfro; field of view 10.07 mm. Courtesy of Mike Bowers.

An interesting tuft of light blue needles was recently observed in a polished modified cube of rock crystal quartz (figure 1). The needles nucleated on a nearly invisible quartz crystal with the tuft tapering toward the opposite end (figure 2). When the tuft was examined looking parallel to the optic axis of the host quartz using cross-polarized light, the small included quartz crystal surrounded by the blue needles stood out in high relief due to the crystallographic misalignment with the host quartz. It was also interesting to note that the included quartz was perched at the apex of a twinned sector of the host quartz (figure 3). While the needles were located too deep within the quartz to conclusively identify with Raman spectroscopy, their appearance (in the author’s experience) suggests they may be pale blue tourmaline. This beautiful inclusion in rock crystal quartz is a striking example of a microfeature in a gem cut to showcase an inclusion.

Core quartz crystal surrounded by blue needles.
Figure 3. When the host quartz is examined looking parallel to the optic axis, the core quartz crystal stands out in high relief and is interestingly located at the apex of a twinned sector of the host. Photomicrograph by Nathan Renfro; field of view 9.32 mm. Courtesy of Mike Bowers.

Source: gia.edu Nathan Renfro

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