Pietersite is the tradename for an aggregate rock predominately composed of hawk's eye and tiger's eye. It is usually a dark blue-gray in color, with rusty browns, reds and golds as well. Though it is a member of the tiger's eye family, Pietersite differs in appearance, with streaks and swirls going in every direction.
Sid Pieters discovered Pietersite in Namibia in 1962. He registered the find in Britain and published his discovery in 1964, and the stone was named in his honor. Though many believed that Pietersite could be found only in Namibia, in 1993 a similar stone was discovered in China's Hunan province. Chinese Pietersite did not enter the gemstone market until 1997. Due to limited production in both China and Namibia, the stone is difficult to find.
Pietersite is a riebeckite, where one mineral smoothly becomes another within the same rock. This results in the chatoyancy, or "cat's eye effect," seen in both Pietersite and tiger's eye rocks. Pietersite looks more chaotic than tiger's eye, however. Its variegated colors and randomly directioned streaks result from the breaking apart of its composite minerals before quartz reformed and cemented those minerals through geologic processes. Hence Pietersite is "brecciated," an Italian word that means a combination of minerals and rock held together by a fine-grained sediment.
Pietersite appears on the market almost exclusively in cabochons; that is, gemstones polished into small, rounded shapes instead of faceted. Cabochons are the easiest way to maximize PIetersite's unique beauty, as a tall and rounded cut best showcases its chatoyancy. Gemcutters must be quite careful with Pietersite, as it must be cut parallel to the length of its fibers.
Cleaning and Care
Polishing Pietersite with a soft cloth is the best way to keep the stone clean. It is also important to keep Pietersite away from household cleaning products and extremes in temperature, as these may have an adverse effect on the gem's coloration. Though Pietersite is not a particularly soft stone (since it has some quartz in it), it should still be stored in a fabric-lined case away from other stones to prevent scratching.
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