MALACHITE AND A METHOD FOR PREPARATION THEREOF Russian patent published in 2004 - IPC

FIELD: imitation jewelry. SUBSTANCE: invention relates to preparing artificially grown stones for jewelry industry, arts and crafts, and chemical industry. Malachite constitutes basic copper carbonate: Zn⁺² or Zn₂[CO₃](OH)₂ (99.509-99.15%) with impurities and zinc compounds (calculated as ZnCO₃•Zn(OH)₂) in concentration of 0.2 to 0.9 wt %, in particular Fe₂O₃, or Na₂O (0.48-0.58%), whereas impurities are represented by Cu₂[CO₃](OH)₂ (0.1-0.2%), CuCO₃Cu(OH)₂ (0.01- 0.1%), and residual ammonium ion in intercrystalline space. Preparation of malachite involves evaporation of basic copper carbonate and basic zinc carbonate in aqueous ammonium carbonate solution. Zinc-to-copper weight ratio in solution being evaporated ranges from 0.018 to 0.09, preferably 0.037-0,049. Evaporation is associated with condensation of gas-vapor mixture NH₃/CO₂/H₂O to form aqueous ammonium carbonate solution. The latter is used to dissolve basic copper carbonate in aqueous ammonium carbonate solution. EFFECT: enabled preparation of polycrystalline with specified thickness and not differing qualitatively from best species of naturally occurring malachite. 25 cl, 1 dwg, 1 tbl, 16 ex