Stilbite-Ca with Calcite

Zeolite specimens from Iceland are seldom seen nowadays because as far as I understand, collecting is mainly, if not entirely, prohibited.  It is easy to imagine, given Iceland’s active geological setting, the size and quality of such specimens it has produced over the years.  In this case we have a small cabinet specimen, beautifully composed of milky white, double terminated scalenohedral Calcite crystals to 2.8 cm richly scattered over, and contrasting against, a botryoidal surface of yellowish buff Stilbite-Ca crystals covering a small matrix of mid to light grey basalt.  Stilbite-Ca is a Zeolite Group mineral and forms excellent plumes averaging 2.5 to 3 cm tall, sections through which can be studied around the edges of the specimen.  A fine display specimen of well crystallised Calcite coating equally well crystallised Stilbite-Ca.  Three nice old labels accompany this: two from collectors and one, Krantz & Comp. (Berlin).