HISTORY, NAME, LOCALITIES: Various varieties of actinolite have been known since antiquity. Its name is derived from the Greek aktino, meaning “ray,” alluding to its radiating crystal habit. Occurrences are widespread with important sources in the United States (Vermont, Nevada, California), Canada, Portugal, Japan, and Switzerland.
MINERALOGY, PROPERTIES, OCCURRENCE: Actinolite [basic calcium magnesium iron silicate, Ca2(Mg,Fe)5(Si8O22(OH)2], pronounced ack-TINN-o-lite, is an inosilicate or chain silicate of the amphibole group of rock-forming minerals that occurs mainly in contact and regionally metamorphosed dolomite rock. Actinolite crystallizes in the monoclinic system as light-to-dark green, flattened blades and radiating fibers. It has a Mohs hardness of 5.5, a vitreous luster, perfect cleavage in two directions, and a specific gravity of 3.0-3.5. The fibrous variety is a type of asbestos; the dense, cryptocrystalline variety is nephrite jade.
METAPHYSICAL PROPERTIES, LORE, USES: Metaphysical practitioners believe that green actinolite has the healing powers of jade, repells negative thoughts, and enhances physical harmony and balance. The nephrite cryptocrystalline variety, once known as “axe stone” for its toughness, was used by primitive cultures for tools and as a sculpting medium; nephrite is one of the two jade gemstones. Until relatively recently when health issues became a concern, fibrous actinolite was mined as a form of asbestos.
COLLECTORS’ INFORMATION: Actinolite is collected for its green color, radiating crystal forms, and different varieties that vary greatly in physical appearance and properties.