1. Similarly, cummingtonite has lower ferric iron and aluminium than anthophyllite. 2. It is the iron endmember of the grunerite-cummingtonite series. 3. Calcium, sodium and potassium concentrations in cummingtonite are low. 4. Cummingtonite tends toward more calcium substitution than related anthophyllite.5. Cummingtonite has also been found in some felsic volcanic rocks such as dacites.6. Cummingtonite shares few compositional similarities with alkali amphiboles such as arfvedsonite, glaucophane-riebeckite.7. With prograde metamorphism cummingtonite and grunerite morph to members of the olivine and pyroxene series. 8. It may be difficult to distinguish cummingtonite from the Mg rich variety in hand specimens. 9. These are : anthophyllite, riebeckite, cummingtonite / grunerite series, and actinolite / tremolite series. 10. Manganese also substitutes for ( Fe, Mg ) within cummingtonite amphibole, replacing B site atoms.
Mobile