Micro-World Gems & Gemology, Summer 2021, Vol. 57, No. 2

Bent Rutile in Rock Crystal Quartz

Amy Cooper and Nathan Renfro

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Brownish red “bent” rutile.
Figure 1. Brownish red “bent” rutile with additional orangy needles displaying sagenitic twinning. Photomicrograph by Nathan Renfro; field of view 11.28 mm. Courtesy of Mike Bowers.

The authors recently examined a polished quartz disk with an unusual rutile (TiO2) inclusion (figure 1). Although rutile in quartz is reasonably common and has been well documented, this “bent” rutile was a fun oddity as it also contained small orangy sagenitic twinned rutile needles extending from the primary bend in the rutile needle. Rutile is most often seen as fine, straight needles (E.J. Gübelin and J.I. Koivula, Photoatlas of Inclusions in Gemstones, Vol. 2, 2005, Opinio-Verlag Publishers, Basel, Switzerland, pp. 627 and 630). Rutile can play many roles as an inclusion and may contribute to phenomenal effects as well as to the bodycolor of an overall transparent colorless quartz (figure 2). While the exact cause of the bent nature of this rutile inclusion is unknown, the stone is a fascinating example of the unusual formation of inclusions in gems.

Bent rutile visible within the polished rock crystal quartz.
 
Figure 2. The polished transparent rock crystal quartz containing the bent rutile inclusion. Photo by Robert Weldon.

Amy Cooper is a senior staff gemologist, and Nathan Renfro is manager of colored stone identification, at GIA in Carlsbad, California.