According to john holland's personality type theory, people who are oriented toward the theoretical and abstract, well-suited for math and science, but who are not particularly good with people are described as

The correct answer is intellectual. Intellectual is being defined as a person that is likely to be associated or engages to research, reflection, or critical thinking in regards to certain things or it could be the society and the environment that the individual is in.

The one that most represents the earths mantle would be the skin since the mantle is the upper part of the earths depths which is just like the skin of an apple.