Complex sentence: This resulted in their depletion in the Earth's crust relative to their solar abundances, though because the minerals they form are nonmetallic they are not as depleted as the siderophile elements.
Split into simpler sentences: This resulted in their depletion in the Earth's crust relative to their solar abundances. Because the minerals they form are nonmetallic they are not as depleted as the siderophile elements.