Magnesia may refer to:

Chemistry and geology

Magnesium oxide Magnesium oxide (MgO), or magnesia, is a white hygroscopic solid mineral that occurs naturally as periclase and is a source of magnesium (see also oxide). It has an empirical formula of MgO and consists of a lattice of Mg2+ ions and O2− ions ...

** Periclase or magnesia, a natural mineral of magnesium oxide * Magnesian limestone (disambiguation) *

Magnesium Magnesium is a chemical element; it has Symbol (chemistry), symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 ...

* Milk of magnesia, a suspension of magnesium hydroxide

Geography

* Magnesia (hypothetical city), a future colony of Knossos, imagined in Plato's ''

Laws Law is a set of rules that are created and are law enforcement, enforceable by social or governmental institutions to regulate behavior, with its precise definition a matter of longstanding debate. It has been variously described as a Socia ...

'' * Magnesia (regional unit), the southeastern area of Thessaly in central Greece * Ancient Magnesia, a historical region of Greece with borders differing from the modern regional unit * Magnesia ad Sipylum, a city of Lydia, now Manisa in Turkey ** Battle of Magnesia, 190 BC, the concluding battle of the Roman–Seleucid War * Magnesia on the Maeander, an ancient Greek city in Anatolia * Magnesia Prefecture, a former prefecture of Greece {{disambiguation, geo