Magnesium chloride is the name for the chemical compound

Chemical compound

A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...

s with the formula

Chemical formula

A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....

s MgCl₂ and its various hydrates MgCl₂(H₂O)_x. These salts are typical ionic halides, being highly soluble in water. The hydrated magnesium chloride can be extracted from brine

Brine

Brine is water, saturated or nearly saturated with salt .Brine is used to preserve vegetables, fruit, fish, and meat, in a process known as brining . Brine is also commonly used to age Halloumi and Feta cheeses, or for pickling foodstuffs, as a means of preserving them...

 or sea water. Magnesium chloride as the natural mineral bischofite

Bischofite

Bischofite is a hydrous magnesium chloride mineral with formula MgCl2·6. It belongs to halides and is a sea salt concentrate dated from the Permian Period...

 is also extracted (solution mining) out of ancient seabeds; for example, the Zechstein

Zechstein

The Zechstein is a unit of sedimentary rock layers of Middle to Late Permian age located in the European Permian Basin which stretches from the east coast of England to northern Poland...

 seabed in northwest Europe.