The major difference in the products of VCS and MCP experiments was that, in MCP no formation of side products such as Zr2ON2 or Mg3B2O6 was observed, as opposed to VCS. Another difference was in the leaching parameters; leaching of MCP products in 1 M HCl for 30 min was sufficient to remove MgO from the products, whereas in VCS a wet grinding step was necessary before leaching. Moreover, leaching had to be performed in 5 M HCl/water solution for 2.5 h so as to remove the side products.