BRUCITE

ABOUT THE SPECIMEN Top color saturation on this lemon-yellow brucite! Killa Saifullah is known for producing some of the finest extant brucite known, although most of what you'll find from the locality is loose, detached from matrix. Here we have a rather large crystallized column “wedged” between two chunks of green host rock. Beautiful color and contrast!   VIDEO   MORE INFO The brucite from Killa Saifullah occurs within serpentinized ultramafic rocks of ophiolitic origin. Formation takes place during low-temperature hydrothermal alteration of forsteritic olivine at temperatures below 300°C. The crystals develop through metamorphic-metasomatic processes involving magnesium-rich fluids circulating through the host serpentinite. Individual brucite crystals display perfect basal cleavage and typically form as platy hexagonal crystals up to 8cm in diameter. The specimens exhibit characteristic colorless to pale green coloration with pearly luster on cleavage surfaces. Associated minerals include serpentine group minerals and magnetite. This occurrence represents typical retrograde metamorphic conditions during serpentinization of ultramafic rocks, where brucite forms as a major phase in the hydration reaction sequence.