Abstract: The humic-mineral agent from naturally occurring carbon-series humites and caustobioliths comprises humic acids and salts thereof, naturally hydrated humic acids, hydrolyzed humic acids, hydrated and hydrolyzed humic-mineral and mineral complexes of parent carbon-series humites and caustobioliths chemically bound to the naturally hydrated humic acids. The method for preparing a humic-mineral agent comprises crushing and disintegrating of carbon-series humites and caustobioliths and mixing them with an alkali. The carbon-series humites and caustobioliths are crushed and disintegrated when their moisture content is close to the natural level at which humic acids are in a naturally hydrated state, hot water is added to the. Next an alkali is added thereto and the mixture is hydrolyzed till obtaining the end product having consistency from viscous-flow to plastic and the pH value of from 6.5 to 8. The method for detoxication of polluted soil.