Cummingtonite is a common component of some regional metamorphic rocks. If more intense metamorphism were to occur the minerals hypersthene , enstatite or olivine are produced at the expense of cummingtonite. Retrograde metamorphism can conversely restore cummingtonite as well as other iron-magnesium amphiboles. Asbestos has many industrial uses despite some health risks and is made from different minerals, all with a fibrous habit. Serpentine and tremolite asbestos are considered the better varieties due to their greater flexibility and tensile strength, but cummingtonite asbestos has its uses and is being mined for this reason in South Africa.
Color is a dark grayish or greenish-brown and dark green.
Luster is silky to vitreous. Crystals are translucent to opaque. Crystal Habits include fibrous, lamellar and radiating masses. Twinning is common and is either simple or lamellar. Fracture is splintery.