What could be an economic factor that prevents the maximum exploitation of this resource

Can someone me with questions 15 to 17 plz.

What best discribes the relationship between wavelength and frequency in a electromagnetic wave

Pegmatites are igneous rocks in which the individual minerals are very large. typically, the minerals are all light-colored quartz, feldspar and muscovite. if you were given a black and white photograph of a pegmatite in a quarry (where the rock has been blasted and broken), what physical properties could you use to identify those three minerals in this hypothetical photo? describe each mineral and the specific diagnostic properties. be specific.