This study was carried out to obtain economically green and red purple pigment based on Cr₂O₃-Al₂O₃ and K₂Cr₂O₇-Al₂O₃-P₂O₅ system by calcining the mixed material of Cr₂O₃, A1₂O₃, Al（OH）₃, K₂Cr₂O₇ and P₂O₅ at various calcination conditions.
The composition of excellent color stain developed in this study is Cr₂O₃·1.5 Al₂O₃ for green and K₂Cr₂O₇·36-38 Al（OH）₃·P₂O₅ for red purple at 1300 ℃ for 4 hours firing. By X-ray diffraction analysis, following fact was known ;
1） Cr₂O₃·1.5 Al₂O₃ pigment forming solid solution between Cr⁺⁺⁺ and Al⁺⁺⁺ at 1300 ℃, green color is more bright than others.
2） But the color of K₂Cr₂O₇-Al₂O₃-P₂O₅ system pigment is due to form amorphous complex between P₂O₅ and others for showing same X-ray patterns at various color conditions.