This specimen is an example of a mineral that formed in a metamorphic environment.
High pressure and temperature prevail at considerable depth within Earth. These pressure and heat conditions result in the rearrangement of the atomic structures in certain minerals, transforming them into others with different structures and compositions.
The process known as thermal metamorphism involves heat alone. Large masses of hot silicate-rich fluids (magma) intruded into existing crustal rock can bring about thermal metamorphism. During this metamorphic process new minerals are formed.