Brucite - Mg(OH)2
Named in 1824 by Francois Sulpice Beudant in honor of Archibald Bruce, physician, early American mineralogist, editor of American Mineralogical Journal, and who first described the species. A fibrous variety of Brucite is called nemalite. Brucite has a layer structure with hydroxyl (OH
-) groups in hexagonal close packing. Each Mg is octahedrally coordinated to six O
-- groups and these octahedra share edges to form the layers. Brucite is a common alteration product of periclase, which is commonly formed in metamorphosed dolomites. Brucite is a common low-temperature hydrothermal mineral in metamorphosed limestones and chlorite schists and is often found serpentinized dunites.
Optical Properties:
•
Form: Is typically in flattened tabular crystals with rare rhombohedral terminations. Also found in lamellar and fibrous aggregates and as foliated masses.
•
Cleavage: Perfect in one direction, basal.
•
Relief: Moderate.
•
Birefringence: High.
Bibliography
• Bucher, K., & Grapes, R. (2011). Petrogenesis of metamorphic rocks. Springer Science & Business Media.
• Fossen, H. (2016). Structural geology. Cambridge University Press.
• Howie, R. A., Zussman, J., & Deer, W. (1992). An introduction to the rock-forming minerals (p. 696). Longman.
• Passchier, Cees W., Trouw, Rudolph A. J: Microtectonics (2005).
• Philpotts, A., & Ague, J. (2009). Principles of igneous and metamorphic petrology. Cambridge University Press.
• Shelley, D. (1993). Igneous and metamorphic rocks under the microscope: classification, textures, microstructures and mineral preferred-orientations.
• Vernon, R. H. & Clarke, G. L. (2008): Principles of Metamorphic Petrology. Cambridge University Press.
• Vernon, R. H. (2018). A practical guide to rock microstructure. Cambridge university press.
Photo
Micaceous brucite crystals (colorless) in a marble. PPL image, 2x (Field of view = 7mm) |
Micaceous brucite crystals (high birefringence) in a marble. XPL image, 2x (Field of view = 7mm) |
Micaceous brucite crystals (high birefringence) in a marble. XPL image, 2x (Field of view = 7mm) |
Micaceous brucite crystals (colorless) in a marble. PPL image, 2x (Field of view = 7mm) |
Micaceous brucite crystals (high birefringence) in a marble. XPL image, 2x (Field of view = 7mm) |
Micaceous brucite crystals (colorless) in a marble. PPL image, 2x (Field of view = 7mm) |
Micaceous brucite crystals (high birefringence) in a marble. XPL image, 2x (Field of view = 7mm) |
Micaceous brucite crystals (colorless) in a marble. PPL image, 2x (Field of view = 7mm) |
Micaceous brucite crystals (high birefringence) in a marble. XPL image, 2x (Field of view = 7mm) |
Micaceous brucite crystals (high birefringence) in a marble. XPL image, 2x (Field of view = 7mm) |
Micaceous brucite crystals (high birefringence) in a marble. XPL image, 2x (Field of view = 7mm) |
Cristalli micacei di brucite (alti colori di interferenza) in un marmo. Immagine a NX, 2x (lato lungo = 7mm)
Micaceous brucite crystals (high birefringence) in a marble. XPL image, 2x (Field of view = 7mm) |
Micaceous brucite crystals (colorless) in a marble. PPL image, 2x (Field of view = 7mm) |
Micaceous brucite crystals (high birefringence) in a marble. XPL image, 2x (Field of view = 7mm) |
Micaceous brucite crystals (high birefringence) in a marble. XPL image, 2x (Field of view = 7mm) |
Micaceous brucite crystals (colorless) in a marble. PPL image, 10x (Field of view = 2mm) |
Micaceous brucite crystals (high birefringence) in a marble. XPL image, 10x (Field of view = 2mm) |
Micaceous brucite crystals (colorless) in a marble. PPL image, 10x (Field of view = 2mm) |
Micaceous brucite crystals (high birefringence) in a marble. XPL image, 10x (Field of view = 2mm) |
Micaceous brucite crystals (colorless) in a marble. PPL image, 10x (Field of view = 2mm) |
Micaceous brucite crystals (high birefringence) in a marble. XPL image, 10x (Field of view = 2mm) |
Micaceous brucite crystals (colorless) in a marble. PPL image, 10x (Field of view = 2mm) |
Micaceous brucite crystals (high birefringence) in a marble. XPL image, 10x (Field of view = 2mm) |
Micaceous brucite crystals (high birefringence) in a marble. XPL image, 10x (Field of view = 2mm) |
Micaceous brucite crystals (high birefringence) in a marble. XPL image, 10x (Field of view = 2mm) |
Micaceous brucite crystals (high birefringence) in a marble. XPL image, 10x (Field of view = 2mm) |
Micaceous brucite crystals (high birefringence) in a marble. XPL image, 10x (Field of view = 2mm) |