Apatite is the name given to a group of phosphate minerals that are widely distributed in all rock types, usually in tiny crystals spread throughout the host rock. It is often green in color but can also be blue, or yellow. It can form large crystals in contact metamorphic rocks. It is the mineral that makes up tooth enamel in all vertebrate animals. It is sometimes used to make fertilizer.
Apatite is a mineral of medium hardness and is used to represent 5 on the Mohs scale.