Brucite with pen for scale. From the mineral collection of Brigham Young University Department of Geology, Provo, Utah, Mineral Specimens 177. Courtesy of the U.S. Geological Survey Denver Library Photographic Collection. (Photo by Andrew Silver.)

Formula: Mg(OH)2 Hexagonal


Brucite forms as a result of the alteration or low-grade metamorphism of other magnesium-rich minerals, such as olivine and periclase. It is usually found in ultramafic rocks and marbles with serpentine, dolomite, hydromagnesite and talc.

WOOD COUNTY: Reportedly found in the soapstone mines near Milladore and Rudolph. Some localities are the Trowbridge Mine in the SW NW Sec. 11 T.25N R.5E. and the Something Mine in the NE SW Sec. 15 T.25N R.5E. Associated minerals are serpentine, talc, actinolite, magnetite and almandine (Crowns, 1976).