abstract: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.
Leonarditeisgreat, it lasta very long time, adds a slowrelease form ofcarbon, matches the gravel's color, sinkseasily poses no issues if you disturb and uproot plants.