A neutral double salt of zinc carbonate and zinc hydroxide in 2-to-3 stoichiometric proportions, 2ZnCO₃路3Zn(OH)₂. Zinc basic carbonate is used as a sulfide scavenger for water-base drilling fluid in a concentration of about 0. 1 lbm/bbl per 50 mg/L GGT sulfides (determined by Garrett Gas Train sulfide analysis of the filtrate). The zinc cation reacts with the sulfide anion to form inert zinc sulfide (ZnS).