Which of the following is not true about plagioclase?
(a) It is composed of K mainly
(b) It is composed of either Na, Ca, or Al
(c) It is of massive or crystalline structure
(d) It gives 2 sets of cleavages
The question was posed to me in exam.
This interesting question is from Formation and Descriptive Study of Minerals in division The Study of Minerals of Engineering Geology