Though technically not a Zeolite, Prehnite is found associated with most of the minerals in the Zeolite group, so it has essentially been “adopted”. It has a signature light-green/mint-green/yellowish-green color, but can also be colorless, white or yellow. It is almost always transparent to translucent and has vitreous to pearly luster. It is associated with numerous aesthetic minerals, including Epidote, Quartz, Calcite, Apophyllite, Copper and Gyrolite.
The crystal system for Prehnite is orthorhombic. Common forms include aggregates that can be fanlike, reniform, globular, stalactitic, granular and compact. Also botryoidal, encrusting and elongated formations with rounded ends resembling fingers; thus called “Prehnite Fingers” by collectors. Another notable formation are epimorphs; crystal growth over the surface of another mineral that subsequently dissolves, leaving behind a hollow shell.
Notable locations for quality Prehnite specimens include Australia, Canada, China, France, India, Mali, Namibia, Spain, Tanzania and the USA (Connecticut, New Jersey).