PURPOSE: To provide a composite mountain leather material having excellent water repellency and lipophilicity and useful as a thixotropic agent, a filler, etc., by adsorbing or supporting a specified water-repellent water-insoluble compd. on mountain leather.

CONSTITUTION: Mountain leather (A) which has been optionally subjected to a surfaces treatment and a water repellent treatment and is fibrous clay minerals having may active hydroxyl groups on the surface thereof, such as mountain leather, mountain cork, mountain wood, etc. is mixed with 0.5W75wt.% (based on the amount of the component A) water-repellent water-insoluble compd. (B) having an m.p. of 80W220°C and a carboxyl or carboxylic ester group. If desired, the mixture is heated at 80W220°C to adsorb or support the component B on the component A.