In which of the following igneous rocks and environments would you expect to find unusually high concentrations of rare elements such as lithium, beryllium, and boron?
A)pegmatite; crystallized from a water- rich, highly differentiated, residual magma
B)peridotite; crystallized at depth in the upper mantle
C)pumice lump; crystallized at depth in a mass of intrusive granite
D)basalt dike; fills a vertical fracture at shallow depth

Question

Quizplus · Accepted Answer

Pegmatites are known for having high concentrations of rare elements because they crystallize from water-rich, highly differentiated, residual magmas that undergo fractional crystallization. As the magma cools and minerals crystallize out, the rare elements can become concentrated in the remaining liquid phase, leading to the formation of pegmatites with high concentrations of elements like lithium, beryllium, and boron. The other options would not necessarily have the same concentration of rare elements.

In Which of the Following Igneous Rocks and Environments Would