Apatite is actually three different minerals depending on the predominance of either fluorine, chlorine or the hydroxyl group. These ions can freely substitute in the crystal lattice and all three are usually present in every specimen although some specimens have been close to 100% in one or the other. The rather non-inventive names of these minerals are Fluorapatite, Chlorapatite and Hydroxylapatite. The three are usually considered together due to the difficulty in distinguishing them in hand samples using ordinary methods.
An irony of the name apatite is that apatite is the mineral that makes up the teeth in all vertebrate animals as well as their bones. Get it? Apatite - teeth! Anyway, the name apatite comes from a Greek word meaning to deceive in allusion to its similarity to other more valuable minerals such as olivine, peridot and beryl.
Apatite is widely distributed in all rock types; igneous, sedimentary and metamorphic, but is usually just small disseminated grains or cryptocrystalline fragments. Large well formed crystals though can be found in certain contact metamorphic rocks. Very gemmy crystals of apatite can be cut as gems but the softness of apatite prevents wide distribution or acceptance of apatite as a gemstone.
Physical properties of Apatite:
Color: Transparent to translucent, usually green, less often colorless, yellow, blue to violet, pink, brown.
Stone Type/Family: A member of the Apatite Group and Phosphate Class
Crystal habit: Tabular, prismatic crystals, massive, compact or granular
Crystal system: Hexagonal Dipyramidal (6/m)
Chemical Composition: Ca5(PO4)3(OH,F,Cl), Calcium (Fluoro, Chloro, Hydroxyl) Phosphate
Cleavage:  Indistinct,  Indistinct
Fracture: Conchoidal to uneven
Mohs scale hardness: 5
Luster: Vitreous to subresinous
Diaphaneity: Transparent to translucent
Specific: gravity 3.16 - 3.22
Polish luster: Vitreous
Optical properties: Double refractive, uniaxial negative
Refractive index: 1.634 - 1.638 (+.012, -.006)
Pleochroism: Blue stones - strong, blue and yellow to colorless. Other colors are weak to very weak.
Ultraviolet fluorescence: Yellow stones - purplish pink which is stronger in long wave; blue stones - blue to light blue in both long and short wave; green stones - greenish yellow which is stronger in long wave; violet stones - greenish yellow in long wave, light purple in short wave.
Location: Brazil, Canada, Mexico, Madagascar, Norway, Russia, USA
Rarity: Relatively Common
Fun Fact: Apatite is the mineral that makes up the teeth in all vertebrate animals as well as their bones.
Metaphysical properties of Apatite:
Clarity, Spiritual Guidance, Self Expression
Primary Chakras: Throat, Third Eye
Astrological sign(s): Gemini, Libra
Vibration: Number 9
Blue Apatite energetically acts as a hunger suppressant. Simply wear or carry a piece with you throughout the day. Blue Apatite also eliminates blockages and returns the body to balance. Blue Apatite can cleanse the aura of cluttered energies, bringing a renewed sensation to the body. Blue Apatite is a good stone to help balance the chakras, as well as the energies of Yin and Yang.
Blue Apatite enhances manifestation of ideas to reality and facilitates getting results.
It has traditionally been associated with humanitarian efforts and teaching. Blue Apatite is also known for bringing clarity of mind and expansion of insights, and is especially helpful when diligent study is needed to uncover the truth.
Blue Apatite enhances communication and self-expression on all levels, making this a great stone for teachers. Blue Apatite encourages openness and ease in social situations, a quality that makes it especially useful for autistic children. Blue Apatite acts as a good balancer of energies, emotions, chakras, and subtle bodies, as well as the male and female aspects of the self.
Blue Apatite can help to effectively work within the dream state to form solutions to perplexing problems. Those who are overemotional can benefit from Apatite's ability to highlight logical solutions and induce calm states of mind.
Blue Apatite can help to develop psychic gifts and connect the user to higher levels of spiritual guidance. Use Blue Apatite to deepen and maintain focus in meditation. Blue Apatite can also initiate, stimulate, and/or increase the development of psychic abilities, such as clairvoyance and clairaudience.
Used at a physical level, Blue Apatite will focus healing energy on the body's systems, glands, meridians and organs.