- For the community in Canada see Actinolite, Ontario. For the Sailor Moon character, see Shitennou (Sailor Moon).
Actinolite is an inosilicate mineral with the chemical formula
Actinolite is an intermediate member in a solid-solution series
(Mg-rich) and ferro-actinolite
. As seen from the chemical formula
above, Mg and Fe ions
can be freely exchanged in the crystal
structure. Like tremolite
actinolite is regulated as asbestos
Actinolite is commonly found in metamorphic rocks
, such as contact aureoles
surrounding cooled intrusive igneous rocks
It also occurs as a product of metamorphism
of magnesium-rich limestones
The old mineral name uralite is at times applied to an alteration product of primary pyroxene by a mixture composed largely of actinolite. 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
a variety of pyroxene).
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.