Cobalt ores found in China have a high manganese content, which produces a more muted blue-gray color.
2
中国人从中东获得了一种蓝色颜料,这是一种当时在中国很难得到的纯净的氧化钴,这种颜料只含有少量的锰。
From the Middle East the Chinese acquired a blue pigment—a purified form of cobalt oxide unobtainable at that time in China—that contained only a low level of manganese.