greenalite

…is associated with the minerals greenalite (iron-serpentine), minnesotaite (iron-talc), and grunerite (iron-amphibole) in various metamorphic stages. In chemically more complex environments, which, in addition to the above components, also involve lime (CaO) and alumina (Al₂O₃), fayalite may be associated with hedenbergite, orthopyroxene, grunerite, and almandine (iron-garnet).

greenalite, in close association with chert and the iron sulfide pyrite, are characteristic minerals that occur in middle Precambrian iron formations (those about 1.5 to 2.4 billion years old). The chert originally was deposited as amorphous silica; equilibrium between amorphous silica, siderite, and greenalite at…

Greenalite, a species rich in ferrous iron, also has a modulated layer structure containing an island configuration.