Best viewed using Adobe Flash Player (8 or higher).
Download hereGENERAL DESCRIPTION
Brucite is a magnesium hydroxide. It occurs in low temperature hydrothermal veins, near serpentinized ultrabasic rocks. It is also a weathering product of periclase (magnesium oxide is unstable in the presence of moisture). Brucite can be associated to magnesite, dolomite...
The crystals are flattened, with possible rhomboedric terminations and with a pseudohexagonal shape. The brucite can display laminated or fibrous masses. It is transparent to translucent, with a waxy lustre, and with a white or greenish to gray-bluish color.
The deposits of brucite are very few. Among others, Asbestos in Québec, the Mounts Ilmen and the peninsula of Kola in Russia (pale crystals of 5 cm), the manganiferous field of Kalahari in the Republic of South Africa (bluish crystals of 3 cm), Aoste (Italy), Brewster and Woods' s mines (respectively, New York and Pennsylvania, USA).
In France, only one locality of brucite is known: Costabonne in the Pyrénées Orientales.
The type is kept at the National History Museum of London.
Did you know? brucite forms atomic layers that are electrically neutral. One thus finds brucite "inserted" in many other silicated minerals like the minerals of the chlorite group, of the montmorillonite/smectite group but also, and this is amazing, in some sulphides (minerals of the family of the valleriite)!
HISTORY : Species dedicated to Archibald Bruce (1777-1818), American doctor and mineralogist who discovered it
Species described in 1824 by François-Sulpice Beudant, French mineralogist
Type-locality: Castle Point, Hoboken, New Jersey, USA
ANCIENT NAME : Magnésie indigène
CHEMICAL FORMULA : Mg (OH)2
CRYSTAL SYSTEM : Hexagonal
COLOR : White, light green, gray
DIAPHANIETY : Transparent
LUSTER : Waxy
STREAK : White
MORPHOLOGIE : Elongated and tabular crystals
HARDNESS : 2,5
CHEMICAL CLASS: 2,368
DENSITY : IV - Oxides and hydroxides
GROUP : Brucite
STRUNZ CLASS BEFORE 2001 : 4/F.03-10
STRUNZ CLASS AFTER 2001 : 4.FE.05
