The mineral Brucite, commonly referred to as magnesium hydroxide, is rarely known as an example of a mineral. It has a few essential uses in industries. The Brucite is a petty ore from which magnesium is extracted. In some refractories, Brucite becomes an additive. Brucite crystals are in the flattened tabular form, having terminations of exceptional rhombohedral shapes. They also occur as foliated masses, fibrous aggregates and in the lamellar form. Brucite is also of the pseudomorph crystal (appearing in a typical form) of Periclase.
Mg (OH) 2
Derivation of name
It was Archibald Bruce (1777 – 1818), an American mineralogist who discovered Brucite, and this mineral was named after him. Brucite that occurs in the fibrous form is named Nemalite. Brucite is found in either laths or fiber form, generally lengthened to  or perhaps  crystalline direction.
Brucite is a general modification of the Periclase found in marble, a mineral of less-temperature found in metamorphosed lime stones, while serpentinization (W-ik-hydration and metamorphic transformation of ultramafic rock) of dunites (plutonic, igneous, rock of ultramafic composition) and as chlorite schists. Brucite generally occurs linked with Calcite, serpentine or dolomitic schists or even as a modified product of Periclase in crystalline limestone.
Only on rare occasions are Brucite formed into facets. Quebec and Asbestos, are the major resources for this material that you can cut, from which you get a gem that is pale blue in color and of 1+ carats. Cutting of Brucite is a Herculean task. Just a few stones whose facets are formed are identified, and they are in the range of size ½ - 1 carat.
The prominent places where Brucite is found are Shetland island, Unst, England; Black Lake, and Wakefield, Quebec in Canada; Pennsylvania, California, Texas, New York, Gabbs, Crestmore, Berks, Brewster, Wood’s Mine, and Nevada in the USA; and Asota in Italy.
Brucite has the property of thermally decomposing to release water like aluminium hydroxide and hydromagnesite and huntite mixtures. Brucite is made use of as a flame retardant. Besides, it is a major resource of magnesium for industrial use.
Grayish, honey-yellow, white, red with brown tint, greenish and dark brown (manganoan types)
2 ½ to 3 Mohs