The Probert Encyclopaedia of Rocks & Minerals

APOPHYLLITE

Apophyllite (so called from its foliated structure or easy cleavage), also called fish-eye stone is a hydrothermal mineral filling cavities in basalt and tufaceous rocks. It is associated with stilbite, scolecite, calcite, prehnite, analcime. It has the formulae KCa4Si8O2O(OH)ù8H2O and a relative hardness of 5.
Research Apophyllite