Prehnite was named after its discoverer; Colonel Hendrik von Prehn and is an attractive collection mineral that is occassionally used for ornamental stone purposes. Its color is usually a pleasant green and is at times quite unique to prehnite. Typical prehnite forms rather thick crusts with a rough or crystaline texture. Epimorphs (crystal growth over the surface of another mineral) over laumontite crystals are interesting and attractive. Usually the laumontite has dissolved away leaving the hollow crust of prehnite behind.