Pentagonite and Cavansite in Heulandite pocket

Item Description

We love the hot blue color of the best cavansite and have followed these since the 90s when they started coming out! However, even better, is seeing both hot blue minerals together in the same specimen - pentagonite ON cavansite! Pentagonite and cavansite are the same mineral chemically, but different crystal habits induced by different conditions of growth: this is called a dimorph. Same chemistry, different crystallography option chosen by nature when they formed....They almost never occur together, let alone in the same specimen. So, this is mineralogically both rare and shocking; and beautiful for us as collectors. The cavansite cluster is 3 cm tip to tip, and the adjacent pentagonite (which one presumes formed later) has crystals to 1 cm sticking up. The whole cluster of hot neon blue is ensconced in a safe pocket of sparkling off white Heulandite crystals. It is all intact and protected in a pocket of basalt, of a good size for display but not too big. And, the sparkly Heulandite lining the pocket is a nice bonus and helps with the contrasts of texture and color. Pentagonite is really rare on its own but this is a really rare specimen even beyond that, for having the two together; and perhaps only 1 in 1000 cavansites has such an association. Valued $4500-plus. NOTE: most such specimens were described by us and others as being in a stilbite pocket but recent analysis by bert ottens shows this to be Heulandite