Byssolite

Byssolite is a fibrous variety of actinolite, belonging to the amphibole group. It occurs as fine, silky fibers, ranging in color from light green to dark green, sometimes associated with quartz, epidote, or calcite. Formed in metamorphic rocks, it develops soft, radiating fibrous aggregates, characteristic of this variety, and is found in numerous deposits in Europe, Canada, and the United States.