Cummingtonite

Amphibole - Cummingtonite w- chlorite in schist Magnesium iron silicate 3800 foot level Homestake Mine Lawrence COunty South Dakota 2071

Cummingtonite

Cummingtonite is a mineral belonging to the amphibole group. It was first discovered in Cummington, Massachusetts, hence its name. The chemical formula of cummingtonite is (Mg,Fe)7Si8O22(OH)2. It is a common mineral found in metamorphic rocks, particularly in regions with high-grade metamorphism.

Properties

Cummingtonite typically appears in fibrous or columnar crystal formations. It has a dark green to black color and a vitreous luster. The mineral has a hardness of 5 to 6 on the Mohs scale and a specific gravity of approximately 3.0 to 3.4.

Occurrence

Cummingtonite is commonly found in metamorphic rocks such as schists and gneisses. It often occurs alongside other amphibole minerals like grunerite and anthophyllite. Significant deposits of cummingtonite have been discovered in various locations around the world, including the United States, Canada, and Finland.

Uses

Cummingtonite does not have significant industrial uses due to its fibrous nature and asbestos-like properties. However, it is of interest to mineral collectors and researchers studying metamorphic processes.

Health Concerns

Like other amphibole minerals, cummingtonite can pose health risks if inhaled as fine particles. Prolonged exposure to cummingtonite dust may lead to respiratory issues and lung diseases. It is important to handle this mineral with caution and use appropriate protective equipment when working with it.

See Also

• Amphibole
• Metamorphic rock