Assertion: calcium oxide's magnesium oxide | /r/Synonym | magnesia alba
Facets:
value: historically
type: TEMPORAL
Source sentences:
text: Magnesium oxide was historically known as magnesia alba (literally, the white mineral from magnesia – other sources give magnesia alba as MgCO 3 ), to differentiate it from magnesia negra, a black mineral containing what is now known as manganese.