Humic Acid : Organic acids of indefinite composition in naturally occurring leonarite lignite. The humic acids are the most valuable constituent. See: Lignite. (Bu D11)
The Mudblogger (Oilfield, Energy and Related Photographs), Oil Field Glossary, TX, USA 2014. http://mudblogger.com/oilfield-glossary/, (Oil - Amer) {777}