Question

The felspar minerals are free from __________

(a) Iron

(b) Iron and manganese

(c) Magnesium

(d) Iron and magnesium

This question was addressed to me by my college professor while I was bunking the class.

I'd like to ask this question from Formation and Descriptive Study of Minerals in section The Study of Minerals of Engineering Geology

Answer 1

The correct choice is (d) Iron and magnesium

The explanation: The felspar group minerals are generally light in colour, because of the absence of Fe and Mg. The minerals have lower specific gravity (generally around 2.6), have doubly cleavage and a hardness varying between 6-6.5.