Pectolite
Cedar Mountain Stone Quarry
Mitchells, Virginia

The pectolite crystals shown in this picture are 7cm across

Pectolite NaCa₂Si₃O₈(OH)

Inosilicates; hydrous calcium sodium silicate, often with some manganese

Color and Luster: Colorless, white, grayish; vitreous, silky; streak white

Hardness: 4.5-5

Cleavage: Perfect, two directions at nearly 90°

Fracture: Splintery, uneven, brittle

Crystals: Triclinic, distinct crystals rare, usually compact and botryoidal masses with radial fibrous structure

Photo by Mary Sutherland

Descriptions taken from
The Audubon Society Field Guide to North American Rocks and Minerals