Periclase is a magnesium mineral that occurs naturally in contact and is a major component of most basic refractory bricks. It is a cubic (Mg ). In nature it usually forms a solid solution (FeO) and is then referred to as ferropericlase
It was first described in 1840 and named from the Greek περικλάω (to break around) in allusion to its cleavage. The type locality, Somma-Vesuvius, Campania
The old term for the mineral is magnesia. Stones from the Magnesia contained both magnesium oxide and hydrated magnesium carbonate as well as iron oxides). Thus these stones, called Stones from Magnesia in antiquity, with their unusual magnetic properties were the reason the terms magnet and magnetism were coined.
Periclase is usually found in marble produced by metamorphism. It readily alters to brucite
In addition to its type locality, it is reported from Predazzo , Trentino; Carlingford, County Louth and the island of Muck , Spain; the Bellerberg Volcano district, Germany; Nordmark , Varmland, southern Ural Mountains , Russia. In the US it occurs at the Crestmore quarry, Riverside County, California; Tombstone, Arizona district, Nye County, Nevada , it occurs at Oka, west of Cowell , South Australia
The crystal structure of periclase corresponds to that of halite and has been studied extensively due to its simplicity. As a consequence, the physical properties of periclase are well known, which makes the mineral a popular standard in experimental work. The mineral has been shown to remain stable at pressures up to at least 360 GPa