Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Silica fume, also known as microsilica, is a fine-grain, thin, and very high surface area silica. It is sometimes confused with fumed silica (also known as colloidal silica and pyrogenic silica). These materials have different derivations, technical characteristics, and applications. Silica fume consists of fine vitreous particles with a surface area on the order of 215,280 ft²/lb (20,000 m²/kg) when measured by nitrogen adsorption techniques, with particles approximately one hundredth the size of the average cement particle.