A method to modify quartz particles to be a surface-active material by mechanochemical treatment was successfully developed. The obtained particles had sufficient properties for use as a particulate emulsifier. The particles prepared by mechanochemical treatment had a highly anisotropic surface, and the droplets emulsified by those particles were extremely large and stable because of their stonewall-like structure and high density. The obtained particulate emulsifier was applied to the liquid-liquid extraction process. Consequently it was clarified that the extraction rate increased 3.6 times according to the increase of interfacial area without reducing the mass transfer coefficient.