Colourless to green amphibole mineral, darkening with increased iron content from green to black. It has a prismatic and splintery texture and is abundant in regionally metamorphosed (see metamorphism) rocks such as schists. Actinolite has a monoclinic crystal structure, and it may alter to chlorite. Seealso asbestos.
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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.
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.
Very low- and low-grade metamorphism of mafic volcanic rocks of the Mira terrane (Avalonia), southeastern Cape Breton Island, Nova Scotia.(Report)
Jan 01, 2010; ABSTRACT Late Neoproterozoic (680 Ma to 560 Ma) Avalonian rocks in the Mira terrane of southeastern Cape Breton Island have been...