noun /ˌmæɡˈniːziəm,ˌmæɡˈniziəm,ˌmæɡˈniʒəm/
A light, flammable, silvery metal, and a chemical element (symbol Mg) with an atomic number of 12.
The building looked only like a wall glowing in the firelight, but sometimes a barrage of magnesium blue light made its windowframes jump out of the darkness.
Wikipedia foundation.