In the oil field, leonardite is better known as "lignite" and is predominantly used in water - based drilling fluid. Leonardite Products oil field line of products is called LenOX^®. The colloidal and soluble properties (alkali solubility tests are 70% or higher) of LenOX^®; help in fluid loss control, serve as clay deflocculants and improve filter cake quality. Leonardite can also be modified for use in oil-based drilling fluids.