Pietersite, also called "eagle's eye," was named in honor of Sid Pieters who discovered it in 1962 in Namibia, Africa. Pietersite is a trade name for a dark blue-grey breccia aggregate made up mainly of hawk's eye and tigereye. It is a variety of chalcedony (itself a variety of quartz) with embedded fibers of amphibole minerals in varying degrees of alteration. The fibers cause a blue chatoyancy like that seen in tigereye
Pietersite is almost always cut into cabochons. This is because, to maximize pietersite's chatoyancy, a tall, round cut is required. It is crucial that the cut must be precisely parallel to the length of the pietersite's fibers.