![Cobalt Carbonate](http://psh.ca/cdn/shop/products/MCTC1_{width}x.jpg?v=1642777931)
CoCO3 A very powerful colorant and flux for glazes (<3%) and slips (<15%) typically producing deep clear blues but also pinks, mauves and greens. It decomposes to cobalt oxide on firing and can be used as a substitute for it in recipes (use 1.5 X more). It is less prone to cause specking than the more concentrated oxide.
For more information on cobalt carbonate, see the Digitalfire.com Reference Library of ceramic materials.