noun
A mineral composed of magnesium carbonate (MgCO₃), used as a refractory material and a source of magnesium.
See also: マグネサイト
菱苦土石は耐火レンガの原料として使われる。
Magnesite is used as a raw material for refractory bricks.
Katakana loanword for magnesite, commonly used in scientific and industrial contexts. 菱苦土石 is the native kanji term, more formal and less common in everyday speech.
Compound of 菱 (rhombus, referring to the crystal shape), 苦土 (magnesia, an older term for magnesium oxide), and 石 (stone). The exact historical derivation is uncertain, but the spelling is conventionally associated with the mineral magnesite.