Description | Prehnite, Ca2Al2Si3O10(OH)2 (calcium aluminum silicate hydroxide), is an attractive mineral and is occassionally used for ornamental stone purposes. Typical prehnite forms rather thick crusts with a rough or crystaline texture. The color is usually a pleasant green and is at times distinctive of prehnite. Other similar minerals include gyrolite, smithsonite and hemimorphite. Prehnite is harder than these and lacks smithsonites luster. Hemimorphite is usually blue and gyrolite is not as glassy. Prehnite can be associated with many nice minerals and can make a fine specimen on its own. |