It is a common alteration product of periclase in marble; a low-temperature hydrothermal vein mineral in metamorphosed limestones and chlorite schists; and formed during serpentinization of dunites.

Brucite is often found in association with serpentine, calcite, aragonite, dolomite, magnesite, hydromagnesite, artinite, talc and chrysotile.

Yellow, white and blue brucite with a botryoidal habit was discovered in Qila Saifullah District of Province Baluchistan, Pakistan.

Brucite has also occurred from South Africa, Italy, Russia, Canada, and other localities as well, but the most notable discoveries are the US, Russian and Pakistani examples.

It finds some use as a flame retardant because it thermally decomposes to release water in a similar way to aluminium hydroxide (Al(OH)3) and mixtures of huntite (Mg3Ca(CO3)4) and hydromagnesite (Mg5(CO3)4(OH)2·4H2O).