Leonardite is a soft waxy, black or brown, shiny, vitreous mineraloid that is easily soluble in alkaline solutions. It is an oxidation product of lignite, associated with near-surface mining.[1] It is a rich source of humic acid (up to 90%)[2] and is used as a soil conditioner, as a stabilizer for ion-exchange resins in water treatment,[3] in the remediation of polluted environments and as a drilling additive.[4] It was named after A. G. Leonard, first director of the North Dakota Geological Survey, in recognition of his work on these deposits.[5]
- ^ Klaus K. E. Neuendorf; American Geological Institute (2005). Glossary of Geology. Springer Science & Business Media. p. 369. ISBN 978-0-922152-76-6.
- ^ Tan, K. H. (2003). Humic Matter in Soil and the Environment: Principles and Controversies. CRC Press. p. 26. ISBN 978-0-203-91254-6.
- ^ The mineral industry of North Dakota, USGS report on non-fuel minerals in North Dakota
- ^ Hoffman, G.L., Nikols, D.J., Stuhec, S., Wilson, R.A. Evaluation of Leonardite (Humalite) Open File Report 1993-18, Resources of Alberta, Alberta Geological Survey Archived 2009-05-01 at the Wayback Machine
- ^ Odzoba, D.M., Blyth, J.C., Engler, R.F., Dinel, H. & Schnitzer, M. 2001. Leonardite and humified organic matter. In Ghabbour, E.A. & Davies, G. (eds.) Humic Substances: Structures, Models and Functions (Special Publication), Royal Society of Chemistry 388pp. Archived 2011-06-27 at the Wayback Machine