magnesite

This term refers specifically to the naturally occurring mineral form of magnesium carbonate. It is primarily used in geological and industrial contexts, such as the production of refractory materials for furnaces or as a precursor to magnesium oxide.

In a technical or chemical context, it is distinguished from other magnesium salts or synthetic carbonates. Because it describes a specific mineral species, it is typically treated as an uncountable mass noun when referring to the substance in general.