| Magnesium-rich amphiboles such as anthophyllite, cummingtonite, and tremolite are colourless or light in colour. |
| Gedrite and cummingtonite coexist with garnet in rocks enriched in aluminum and iron. |
| Accessory chlorite, magnetite or ilmenite, titanite, apatite, partly chloritized biotite, epidote, pyrite and sometimes cummingtonite, are present. |
| The two minerals can have similar distinctive brown colors and are hard to differentiate from each other, although cummingtonite is typically darker and slightly denser. |
| This rock is a dark gray schistose rock containing radiating aggregates of cummingtonite and occasionally pyrrhotite. |
| Rocks containing cummingtonite or grunerite are characteristic of metamorphosed iron formations associated with iron oxides, iron-rich sheet silicates, carbonates, and quartz. |
