Tuesday, May 31, 2016

Why is massive rose quartz pink?

I have always enjoyed collecting quartz, and massive rose quartz is one of my favorites. There are some interesting new findings about what causes its coloration, and this post with help inform you about some of them. You might note that researchers use the adjective “massive” to describe rose quartz. This is done in order to differentiate it from euhedral (nice, angular crystals) of rose quartz.

A polished specimen of massive rose quartz, 3.75 inches high.

Massive rose quartz is one of the common colored varieties of quartz and found at numerous localities worldwide. A few of the areas where multiple localities are known include: Brazil, California (Riverside County), Montana, South Dakota, Norway, and Madagasgar. Massive rose quartz is commonly found in granitic pegmatities. It is less commonly found in hydrothermal veins.

Unpolished massive rose quartz (about 6.5 inches long), from Minas Gerais mine in Brazil.

So, what causes the pink color of massive rose quartz? Over the years, there have been various explanations, but the one that has been meticulously researched by Caltech mineralogists in recent years has proven the presence of pink nanofiber inclusions, which are related to the pink mineral dumortierite, a boron-bearing silicate. These pink nanofibers are 0.1 to 0.5 micro meters in width [about 0.00002 inches], and they resemble wavy bundles of hair-like fibers.

Massive rose quartz is always slightly to highly cloudy (turbid) and never clear. Its color can range from pale to pink to lavender (even in the same hand specimen, see third picture), and, in some cases, entirely lavender (see fourth picture), or, reportedly, orange.

From left to right: massive rose quartz showing transition from pale pink to pinker to lavender.
Hand specimen is 5 inches in length.

Lavender variety of massive rose quartz.
Hand specimen is 4 inches high.

I obtained much of the above information from the very informative article:  Goreva, J., C. Ma, and G. R. Rossman, 2001. Fibrous nanoinclusions in massive rose quartz: The origin of rose coloration. American Mineralogist vol. 86, pp. 466–472.

Just copy the article title, paste it in the Google Search box, and you can get your own free pdf.

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