NiCO3·2Ni(OH)2. Converts to nickel oxide on firing. Typically produces browns but also pinks, blues and greens depending on glaze chemistry. Zinc crystalline glazes containing it can yield striking turquoise blue zinc silicate crystals on a clear mustard yellow background. If used to replace nickel oxide in a glaze recipe, use 20% more.
For more information on nickel oxide, see the Digitalfire.com Reference Library of ceramic materials.