The shape of this twinned calcite crystal is simply sexy: the combination of sharp pseudotriangular termination, penetration twinning, gemminess, and phantoms is totally unique to this day. This is an exceptional, and impressive, large twinned crystal that is glassy, gemmy and colorless. Unlike most of the English butterfly twins which are robust and thickly 3-dimensional in general, this twin does not extend into a 3rd axis, being no thicker than 2 cm, along its very flat front and back sides. Although there are really fascinating vertical striations on the front and back, there are not protuberances sticking out in all directions as you'd expect for most twins. It is aligned vertically. All similar crystals I have seen from this old find were similarly formed. For that matter, I'm not sure that I have seen another calcite twin quite like this one from ANY other locale but this old classic find (I know they were found in the "old days" but not exactly when. They do turn up only in museums and old collections, it seems; and quite a few went into the Smithsonian and then were used to trade out for other minerals in the mid-1900s). This one turned up in an old collection in California in the late 1990s, and I kept it in my personal calcite collection which I had built til that time. I then sold it into the Stoudt collection of Mexican minerals in 2005. Although not in the Heck collection of Mexican minerals as are most others in this update, this piece is from the Stoudt collection which I also recently acquired, and so fit well with the larger Mexican themed update. Small ones turn up time to time. I have only seldom seen one so good, so big, and in this condition. comes with custom lucite display base. Joe Budd Photos.