This stone is actually quite rare and difficult to cut, so in many cases other types of rock were used as substitutes, for example green feldspar, basalt, and serpentine.

• 这个石头实际上相当稀罕和难于切割，因此在许多情形里其它类型岩石被当作代用品使用，例如绿长石，玄武岩和蛇纹石。