amphibole mineral, an iron-rich sodium silicate. Lithium and magnesium replace iron in the structure to form eckermannite. Both minerals characteristically occur as dark-green crystals in alkali igneous rocks and their associated pegmatites. For chemical formula and detailed physical properties, see amphibole (table)
Learn more about arfvedsonite with a free trial on Britannica.com.
|a chattering or flighty, light-headed person.|
|a children's mummer's parade, as on the Fourth of July, with prizes for the best costumes.|