grunerite

mineral

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Last updated

June 29, 2026

Quick Summary

Grunerite is a variety of amphibole, which is a group of common rock-forming silicate minerals. Amphiboles are typically found in metamorphic and igneous rocks. Grunerite has the chemical formula Fe₇Si₈O₂₂(OH)₂. The name "amphibole" comes from the Greek word for "ambiguous," reflecting the wide variety of compositions and appearances within this mineral group. Amphiboles are characterized by their double chain silicate structure and distinct cleavage angles.12

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olivine
Metamorphic rocks
(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).
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(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).
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amphibole
Chemical composition
The monoclinic cummingtonite-grunerite series exists from about Fe₂Mg₂Si₈O₂₂(OH)₂ to Fe₇Si₈O₂₂(OH)₂. Intermediate amphibole compositions do not exist between anthophyllite and the tremolite-actinolite series. Compositional gaps also exist between the cummingtonite-grunerite series and other calcic amphiboles. Consequently, coexisting pairs of anthophyllite-tremolite
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The monoclinic cummingtonite-grunerite series exists from about Fe₂Mg₂Si₈O₂₂(OH)₂ to Fe₇Si₈O₂₂(OH)₂. Intermediate amphibole compositions do not exist between anthophyllite and the tremolite-actinolite series. Compositional gaps also exist between the cummingtonite-grunerite series and other calcic amphiboles. Consequently, coexisting pairs of anthophyllite-tremolite
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