Actinolite is commonly found in metamorphic rocks. It also occurs as a product of metamorphism of magnesium-rich limestones. Like tremolite, asbestiform actinolite is regulated as asbestos.
The old mineral name uralite is at times applied to an alternative form. The metamorphosed gabbro or diabase rock bodies, referred to as epidiorite, contain a considerable amount of this uralitic alteration.
Some forms of asbestos are formed from fibrous actinolite, the fibres being so small that they can enter the lungs and damage the alveoli.
Some forms of actinolite are used as gemstones. The first is called nephrite, which is one of the two types of jade (the other being jadeite).
Another gem variety of actinolite is the chatoyant form known as cat's-eye actinolite. This stone is translucent to opaque, and green to yellowish green color. This variety has had the misnomer jade cat's-eye. Transparent actinolite is rare and is faceted for gem collectors. Major sources for these forms of actinolite are Taiwan and Canada. Other sources are Madagascar, Tanzania, and the US.