Trapiches are a rare kind of Emerald with the presence of black carbon impurities giving the Emerald a radial six pointed star pattern. It is usually made into oval and round cabochons but can come in different shapes too.
Cumengite - Mexico. On a fully developed specimen, each of the six faces of the boleite's cube are capped with a four sided pyramid of cumengite. The resulting aggregate is a true mineralogical curiosity, a six pointed, 3 dimensional, indigo blue star. There are not many complete specimens in existence and even partial stars are valuable.