Mineral Species: Stilbite

Chemical Formula: (Na2,Ca,K2)Al2Si7O18.7H2O

Chemical Name: Hydrated Sodium Calcium Potassium Aluminium Silicate

Mineral Class: Zeolite Silicate

Mineral Notes: Stilbite is a common zeolite whose crystals tend to clump together into aggregates resembling wheat sheafs. It tends to form in amygdaloidal cavities in basalts and similar rocks. The mineral has recently been redefined into Ca-Stilbite and Na-Stilbite according to the dominant chemical composition. However their close resemblance makes individual identification extremely difficult and therefore most specimens are referred to by the generic group name.

Description: Superbly formed, platy crystals of Stilbite on matrix. Perfect terminations and edges. The mineral has a very attractive pearly luster and a strong white colour. An excellent display specimen.

Location: Condon Quarry, Dracut, Middlesex Co., Massachusetts, USA