Wiktionary
n. (context inorganic compound English) The magnesium salt of carbonic acid, MgCO3; it is a white powdery solid that occurs as magnesite and other minerals; it used as a mild base and in numerous industrial applications
Wikipedia
Usage examples of "magnesium carbonate".
The brightest planetary nebula known (a planetary nebula is an expanding cloud usually surrounding an exploding star called a nova) seems to contain particles of magnesium carbonate: Dolomite, the stuff of the European mountains of the same name, expelled by a star into interstellar space.
One contained a mixture of magnesium carbonate and sodium acetate, the other a twenty-volume solution of hydrogen peroxide.
He dwelt on the old stars that gave birth to us, spitting silicates and magnesium carbonate into space to form planets, hydrocarbons to form ourselves.