Leonardite

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. It is a rich source of humic acid and is used as a soil conditioner, as a stabilizer for ion-exchange resins in water treatment, in the remediation of polluted environments and as a drilling additive. It was named after A. G. Leonard, first director of the North Dakota Geological Survey, in recognition of his work on these deposits.

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