brucite

Brucite is a mineral species with the chemical formula Mg(OH)2. It is a hydrous magnesium hydroxide that forms in low-temperature alteration zones of magnesium-rich rocks and in serpentinite-related hydrothermal environments. It commonly occurs with serpentine minerals, calcite, magnesite, and magnetite, and is found in hydrothermal veins and contact metamorphic rocks associated with ultramafic rocks.

Brucite typically presents as white, colorless, gray, or pale-colored crystals or massive aggregates. It has a vitreous to pearly luster, a white streak, and is transparent to translucent. The Mohs hardness is about 2.5, and it exhibits perfect basal cleavage. Its specific gravity is around 2.4. It is insoluble in water and dissolves in acids. Upon heating, brucite dehydrates to magnesium oxide (MgO) and water at approximately 350–450°C.

Crystal habit ranges from tabular to platy crystals and can occur as massive, fibrous, or granular aggregates. Although relatively rare as a primary mineral, brucite is widely reported in serpentinite complexes and related ultramafic rocks around the world. It commonly occurs with minerals such as talc, chrysotile, lizardite, calcite, and magnesite.

Uses of brucite are mainly tied to its role as a source of magnesium. Calcination yields magnesium oxide (MgO), which is used in refractories and ceramics. Magnesium hydroxide derived from brucite is also used in some flame-retardant applications and as a chemical feedstock in various industrial processes.

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