Cobalt Carbonate MCOBCA 50 gmsCobalt Carbonate MCOBCA CoCO3 A fine, particled, lavender powder used as a colorant in glazes and slips. It is the most stable and reliable colorant. Produces various shades of blue when used alone, and will produce the same shades of blue when used in almost every type of glaze and under various firing conditions. Often used for overglaze brushed decoration.