Rutilated quartz

Rutilated quartz is natural quartz (SiO₂), usually colourless rock crystal, that encloses needles of the mineral rutile (TiO₂). The needles are usually golden, but can also be reddish, brown, silvery grey or, very rarely, green. It is a variety of quartz, not a separate mineral species, and the general name does not specify the colour of the inclusions.

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Full material guide
Material facts

What the material is, where it comes from or how it is made, identification and care, from the cited sources.

Properties

Material type Natural mineral: quartz with mineral inclusions (not a separate species)
Inclusions Rutile (TiO₂) needles, usually golden; also reddish, brown, silvery grey, rarely green
Host mineral Quartz, SiO₂ (usually colourless rock crystal)
Chemical formula (quartz host) SiO₂
Crystal system Trigonal (quartz host)
Mohs hardness (quartz host) 7
Specific gravity (quartz host) 2.65
Refractive index (quartz host) 1.544 to 1.553

Origins & sources

Rutilated quartz is found mainly in Brazil. Mindat records it from Bahia, including Novo Horizonte, and from many other places, among them Australia and Austria. Reddish rutile has also been recovered in Bahia, grey rutile needles overgrown on brookite occur in the material sold as “platinum quartz” from Currelo in Minas Gerais, and silvery grey rutile tufts have been found in quartz in El Dorado County, California. The rutile needles grew first and were then enclosed by the growing rock crystal in quartz-bearing pegmatites. In six-rayed stars, the rutile grew outward from a hematite crystal at the centre.

Identification

Rutile needles in quartz are long and straight, usually golden or red, ranging from golden to brown; silvery grey and, very rarely, green needles also occur. Long thin black needles in quartz, often mistaken for rutile, are tourmaline, which is common in quartz. Gemmological laboratories identify rutile needles by Raman spectroscopy. Lower-quality pieces can be made into doublets with a cap of glass or synthetic quartz, and a rutilated quartz sphere reported in Gems & Gemology in 2020 had a brown half, taken for host rock, that was epoxy resin mixed with mineral powders: its specific gravity of 2.35 is well below that of quartz, and Raman spectroscopy showed resin.

Care

The host is quartz, with a Mohs hardness of 7. JCK advises washing off dust before wiping the stone with a cloth, because dust of similar hardness can leave fine scratches that gradually dull the polish.

History & culture

History

Rutilated quartz was popular in jewellery in the 19th century and regained prominence in the second half of the 20th century, when Bernd Munsteiner and other cutters created innovative faceting styles known as fantasy cuts. Among its other names, Mindat lists “Venus' hair stone” and “flèches d'amour” (French for “arrows of love”), and Gemdat also records “Venus hair stone”.

Cultural meanings

A Japanese retailer says that, because of its golden needles, rutilated quartz has long been said to draw in money, and that it has been loved as a charm for wealth, fortune and business. The same retailer adds that it is said to foster courage, daring and ambition, and to turn worry into the confidence that things will work out.

Sources