Pectolite - NaCa₂Si₃O₈(OH)

Habit: Colorless, white, pale pink, greenish or pale blue. Crystals may be tabular but also commonly acicular, radiating fibrous, spheroidal or columnar; also fine-grained or massive. Silky, subvitreous luster; translucent to opaque. White streak.

Environment: A primary mineral in nepheline syenites. Also found as a hydrothermal mineral in cavities in basalts and diabases and in serpentinites and peridotites.

Etymology: From the Greek pektos, meaning "congealed" or "well put together," in allusion to its resistance to pulverization. Some specimens of pectolite are triboluminescent. They give off light when friction is applied.