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Word of the Week: Cummingtonite

Written by Science

Cummingtonite is a rock mineral which was discovered by Chester Dewey in 1824 in the equally weirdly named town of Cummington, Massachusetts.

It can be found in countries across 4 continents, These countries include the US, Scotland, Sweden, South Africa and New Zealand. Magnesium is the dominant element present in Cummingtonite. The rock forms in a variety of colours: translucent dark green, brown and grey, although it is sometimes colourless. It is also glass-like in appearance. Interestingly, cummingtonite has a perfect cleavage in two directions. This means that the mineral is able to break smoothly along two planes. Therefore, its cleavage makes it more aesthetically pleasing. Furthermore, Cummingtonite is relatively hard. It has a hardness of 5-6 out of 10 on the Mohs scale. This, ironically, is much harder than Dickite (1.5-2) and Fukalite (4).

Cummingtonite is also non-pleochroic, meaning that it looks the same from all angles unlike some minerals which appear to give off different colours. One of the few uses of Cummingtonite is in asbestos, which only comes from the amosite variety of the mineral. There are of course health risks involved in this, but there are still industrial uses for asbestos today, and this is the main reason that Cummingtonite is being mined in South Africa. Conclusively, Cummingtonite is actually a very boring mineral with a somewhat interesting name.

Last modified: 22nd January 2020

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