This mineral is very rare.

He is an excellent student.

I am majoring in embryology at university.

The educational system in Japan consists of six years of elementary school, three years of junior high school, three years of high school, and four years of university.

He is an excellent medical student.

He is an expert in biochemistry.

I am majoring in biochemistry at university.

Sexology is the scientific study of human sexual behavior and sexuality.

The sexology class is very interesting.

I am majoring in biophysics at university.