Hampshire County, Massachusetts
These sheaf-like bundles of stilbite crystals were deposited by hot,
water-rich solutions in cavities and fractures in volcanic rock. The color
variations are caused by the many different orientations of the crystals in
the thin section. Stilbite is a member of the mineral family called
zeolites. Submicroscopic tunnels in their crystal structure, as well as
their chemically sticky surfaces, make zeolites excellent natural filters.
This leads to many industrial applications such as ion exchangers in water
softeners, and as molecular sieves.