mineral
Actinolite
Ca2(Mg,Fe)5Si8O22(OH)2
AI-generated identification · may be incorrectHardness of 5.5 to 6 on the Mohs scale, typically green to dark green in color with a vitreous to silky luster. It features a monoclinic crystal system and distinct prismatic cleavage.
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Physical properties
Hardness of 5.5 to 6 on the Mohs scale, typically green to dark green in color with a vitreous to silky luster. It features a monoclinic crystal system and distinct prismatic cleavage.
Formation & geological history
Forms primarily through regional metamorphism of magnesium-rich and iron-rich rocks, as well as contact metamorphism in limestones.
Uses & applications
Used primarily in lapidary arts for cabochons and carvings, and as a mineral specimen for collectors; fibrous varieties were historically used as asbestos.
Geological facts
Actinolite is a key end-member in the solid-solution series with tremolite and ferro-actinolite. It is also the fibrous component found in some types of jade known as nephrite.
Field identification & locations
Identify by its characteristic green color, fibrous or columnar crystal habit, and occurrence in metamorphic terrains.
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