A very powerful glaze colorant typically used at levels <2% to produce opaque moss greens or blue-greens with cobalt oxide. In glazes containing zinc oxide, the colour shifts to dull beige-brown. Volatility during firing can cause pink “flashing” on remote glazes containing tin oxide. Trace amounts with tin oxide in certain hi-calcium recipes yield pink and crimson. Ceramic stain manufacturers rely on chrome oxide to form or modify synthetic spinels, garnets, sphenes, etc. to produce a remarkable range of colours.