Rutile (or rutilated) quartz is clear or smoky quartz with inclusions of rutile. The rutile needles form lovely patterns like miniature sculptures. Every stone is quite unique and it has become very popular for jewelry over the last few years.
Recently we had an opportunity to buy some rutile topaz, a similar looking gem with the added attraction of topaz's additional hardness and better brilliance. However, as we investigated this gem we discovered that the ribbon-like inclusions in rutile topaz are actually quite different from those in rutile quartz.
The Gemological Institute of America (GIA) published an article in their journal some years ago (Gems & Gemology, Summer 1987) that explored this difference. According to this article, the needle-like inclusions in so-called rutile topaz actually consist of limonite staining that fills hollow tubes in the topaz. In fact rutile is not known to crystallize in a ribbon-like form in topaz.
Limonite is quite a different mineral from rutile. Rutile is titanium dioxide and has an exceptionally high refractive index; much higher than that of diamond. Limonite is not a true mineral, but is composed of a varying mixture of hydrated iron oxide minerals such as goethite and lepidocrocite. Limonite is typically yellow-brown in color, and is used as the basis for the natural earth pigment ochre.
Thus the name rutile topaz is a misnomer. Clearly the name came from the apparent similarity to the better-known rutile quartz, but has persisted even as more accurate information reached the market. One reason is that no one has proposed a more accurate name that would be acceptable to the market - apparently limonite-stained topaz did not catch on.
If you compare a number of different samples of rutile quartz and rutile topaz, you will see many differences. The range of patterns in rutile quartz tends to be much greater, and dense clusters of needles are more common in quartz. The rutile topaz tends to have greater areas of transparency with sparser and more delicate inclusions. Both are equally attractive in their own way.
- First Published: June-22-2010
- Last Updated: September-30-2014
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