Rose Quartz

Two varieties of quartz are commonly called "rose quartz".

1. One is found in translucent masses made of intergrown anhedral crystals. It occurs in different hues of pink, sometimes bluish, sometimes more reddish; irradiation may cause the formation of smoky quartz color centers and add a gray tone.

This variety of Rose quartz is always showing a hazy to translucent character due to microscopic fibrous inclusions of a pink borosilicate mineral related to dumortierite (Applin and Hicks, 1987; Goreva et al, 2001; Ma et al, 2002), which group leader Rossman names "dididumortierite" (Nadin, 2007). These inclusions are probably the result of an exsolution from an initially homogeneous material.

The color of the fibrous mineral as well as the colour of rose quartz is stable up to temperatures of about 575°C (Lehmann and Bambauer, 1978; Goreva et al, 2001) and is also generally stable in ultraviolet light (Goreva et al, 2001), although there have been occasional reports of material that pales quickly in daylight.

Rose quartz is dichroic, reflecting a preferential orientation of the included fibers.

Rose quartz from some localities shows asterism when cut as spheres or cabochons, much like that seen in certain sapphires. It is sometimes called star rose quartz. The six-rayed star is caused by reflections of the light from embedded fibers that intersect at an angle of 60°. The star's position depends both on the location of the light source and the position of the observer (Schmetzer and Krzemnicki, 2006; Killingback, 2008).

Rose quartz is commonly found in the quartz cores of pegmatites and is believed to form at high temperatures, but it has also been found in hydrothermal veins.

This variety is the rose quartz that is used in lapidary and carvings.
Crystals of this type of rose quartz have never been found.

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2. The other variety of pink/rose quartz occurs in well-formed crystals of similar colour: “euhedral rose quartz”. Because of the substantial differences in the physical properties and causes of colour it has been suggested to give the variety of pink-coloured quartz that forms crystals the name "pink quartz"(Hori, 2001) or "Rosaquarz" (German for pink quartz, Rykart, 1995) but neither of these names have found widespread use.

This variety is found as a late formation in pegmatite pockets, often overgrowing smoky quartz crystals in groups of radiating to sub-parallel crystals. According to Maschmeyer and Lehmann (1983), the colour is caused by irradiation-induced colour centers based on aluminum, Al, and phosphorous, P, that replace Si in the atom lattice. A synthetic counterpart has been synthesized, and irradiation-induced P-bearing color centers have found to be responsible for its colour, too, but aluminum was absent (Balitsky et al 1998). The crystals are also slightly dichroic; the strongest colour is observed when the polarization plane is perpendicular to the c-axis.
The colour in both natural and synthetic specimens is very light- and heat sensitive (Balitsky et al 1998). An example for its UV-sensitivity is shown on the photo to the left: a natural specimen was completely bleached within 10 hours of UV irradiation. This is much faster than the bleaching observed in smoky quartz or amethyst, and specimen should be kept in the dark to preserve their colour.

Incorrect uses of the name

The term "rose quartz" has also occasionally been used for quartz that is coloured by other inclusions.

Pale amethyst may be confused with euhedral rose quartz/pink quartz. Amethyst and euhedral rose quartz/pink quartz are both occasionally found overgrowing smoky quartz and may show similar sheet-like surface patterns. The visual distinction between amethyst and euhedral rose quartz/pink quartz is difficult unless the crystals are free-standing. Then the different dichroic behaviour can be used to determine the variety: when the polarization of the light is changed from parallel to the c-axis to perpendicular to the c-axis, amethyst changes its colour from bluish to reddish, whereas euhedral rose quartz/pink quartz changes from a more pale to a more intense pink colour.