text: The term was coined by Joseph Marius DallaValle in his book Micromeritics: The Technology of Fine Particles (1948). It was derived from the Greek words  meaning "small" and  meaning "part". The size range which he covered in the book was from 10 to 10 micrometers. Anything smaller than this but bigger than a molecule was referred to at the time as a colloid but is now often referred to as a nanoparticle. Applications included soil physics, mineral physics, chemical engineering, geology, and hydrology. Characteristics discussed included particle size and shape, packing, electrical, optical, chemical and surface science.