Process for the preparation of aqueous suspensions of brochantite (Cu 4(OH) 6SO 4) or antlerite (Cu 3(OH) 4SO 4) and their mixtures, having a solid content above 10 % by weight by reacting solution of copper sulfate with suspension of copper oxide or copper hydroxide. Process for the preparation of aqueous suspensions of brochantite (Cu 4(OH) 6SO 4) or antlerite (Cu 3(OH) 4SO 4) and their mixtures, having a solids content above 10 % by weight, by reacting an aqueous solution of copper sulfate having a concentration of 6 % - 10 % by weight, with an aqueous suspension of copper oxide or copper hydroxide having a concentration of 15% - 50 % by weight, in a molar ratio SO 4/Cu = 0.25 - 0.40, the copper oxide or hydroxide particles having a mean diameter of 25 Microm or less, the reaction being effected at 40 - 100[deg]C. ACTIVITY : Plant antifungal. MECHANISM OF ACTION : Not given in source material.