Poudretteite: A Rare Gem Species from the Mogok Valley

Abstract

is a region rich in history, tradition, lore, and gems. Myanmar is commonly referred to as the world's premier source of ruby, sapphire, spinel, peridot, and jadeite. In addition, the Mogok Stone Tract plays host to a wide range of other notable gem species and varieties, including amethyst, andalusite, danburite, garnet, goshenite, scapolite, topaz, tourmaline, and zircon. It has also produced a number of very rare gems, such as sinhalite, colorless chrysoberyl, taaffeite, and painite (see, e.g., Kammerling et al., 1994;Themelis, 2000).In November 2000, an Italian dealer buying gems in Mogok was shown a 3 ct faceted gemstone (figure 1) that the local gem merchant/gemologist could not identify (F. Barlocher, pers. comm., 2000). This gemstone was subsequently submitted to the Gübelin Gem Lab for examination and identification. On the basis of the results given in this article, it proved to be the first documented gem-quality specimen of poudretteite, a mineral that has been reported previously from only one source in the province of Quebec, Canada (Grice et al., 1987), and only in small numbers and sizes (see below). These results were also given to R. Schlüssel, who subsequently included poudretteite in his book on Mogok (Schlüssel, 2002). This extremely rare sample permits the first comprehensive gemological description of this material and expansion of the body of analytical data for this mineral by a variety of techniques that had not been used previously.

Analysis of Impurity Effects on the Coloration of Corundum by Laser-Induced Breakdown Spectroscopy (LIBS)

“…Later, more sophisticated tools, such as infrared and ultraviolet visible spectrometers, X-ray fluorescence (XRF), and Raman instruments were developed to meet the analytical needs of gemological laboratories. [4][5][6][7][8] The coloration of a natural gemstone is a prime factor determining its quality and market value. There are multiple origins of color in gem minerals that have been explored in recent years.…”

A Gemological Pioneer: Dr. Edward J. Gübelin

“…This began a popular six-year series in Gems & Gemology on inclusions in gemstones, which in 1953 was compiled into the book Inclusions as a Means of Gemstone Identification. His last contribution to Gems & Gemology, which he co-authored with six other researchers, was "Poudretteite: A rare gem species from the Mogok Valley" (Smith et al, 2003) Dr. Gübelin's generosity went beyond just lending his name and prestige to the award. Each year, he insisted on writing a check that would cover the prize money.…”