Fine Phosphophyllite crystals nearly fill the void of a fossil clam shell with the center area still open. The center void has dozens of sharp terminations surrounding the middle. Some crystals show the classic "swallowtail" twinning habit and all are a translucent apple green. This is one of the very best specimens I have seen from a small find made in 2009-2010. Phosphophyllite in sizable crystals is rare and one of the "holy grail" species. Outside of Bolivia nearly all other specimens are quite small, measured in millimeters, and most are micros. This locality is about 45 KM from the more famous mines at Cerro Rico which is also in Potosi, Bolivia. The best specimens from Cerro Rico are highly prized, being both rare and some the most expensive mineral specimens in the world. This smaller find at Huaylliani more than a decade ago was huge news in the mineral world back then. While the crystals from here are not as gemmy and clear as the best from Potosi, they are still very fine and would rank as the second best in the world. The find is long ago finished and these are now quite prized as well. The largest crystals on this piece are over 2 CM but most are smaller. An unusual piece, very large for the area, this has both lustrous areas and some lightly frosted crystal faces. Minimal matrix, this is over 78 grams of nearly pure Phsopophyllite. The shape of the clam shell is still somewhat visible on the backside but the open vug of the green Phosphophyllite crystals is the real star here. In excellent condition overall, a few small Iron stains are present on some edges though the crystals are very clean. An outstanding piece from this important find.