Obviously, at each step the percentage of felspar and phosphorus is less and less until in the final concentrates the percentage of iron oxide is 91 to 93 per cent. 弗兰克·刘易斯·戴尔.爱迪生的生平和发明.
The decomposed felspar of some varieties of granite yields the kaolin used in porcelain manufacture. 佚名.神奇的知识之书.
Granite quarried anywhere in which felspar predominates is not well adapted for buildings, as it cracks and crumbles down in a few years. 佚名.神奇的知识之书.