Semi-Precious Gemstones: Apatite
Apatite & Cat's Eye Apatite used in Jewelry
Source: Brazil, Canada, Colombia, Germany, Madagascar, Mexico, Russia, Sri Lanka, USA
Apatite is not a single mineral, but a phosphate mineral group consisting of chlorapatite, fluorapatite, and hydroxylapatite. Each individual mineral has a certain level of chlorine, fluorine, or hydroxy in varying amounts and combinations. The most common gem variety is a translucent to transparent semiprecious gemstone that is steadily increasing in popularity within the jewelry trade, and its greenish-blue 'seawater' color makes it an inexpensive, although somewhat soft substitute for aquamarine.
Apatite displays strong fluorescence under short wave ultra-violet light. There is a particularly intense, and deeply saturated, geenish-blue (aka "swiss blue") variety from Madagascar which is known as "neon apatite." There is also a darker, yellowish-green varietie that is sometimes referred to as "asparagus stone." The name "apatite" is derived from the Greek word "apate" meaning "deceit" or "to deceive."
Apatite rough and polished beads (Photos: public domain)
Apatite is occurs within igneous rock, metamorphic rock, and sedimentary rock, with large crystals being found primarily in metamorphic rock. Apatite is found in association with cassiterite, feldspar, quartz and rutile.
Gemmy apatite crystals can be facet cut but the softness lends itself to be cut en cabochon. There are also chatoyant varieties of apatite called appropriately "cat's eye apatite" which is typically cut into a cabochon. The mineral hydroxylapatite is the major component of tooth enamel, and fluorapatite (aka fluoroapatite) is used in fluoridated water, to help strengthen teeth by exchanging hydroxyl ions for fluoride ions.
Apatite Crystallography, Chemistry, Physical Properties
Apatite Optical Properties
Bibliography and Reference on Apatite
1. Paul R. Shaffer, Rocks, Gems and Minerals  . Martin's Press
3. Renee Newman, Gemstone Buying Guide . International Jewelry Publications; 2nd edition
3. Antoinette L . Matlins, Antonio C. Bonanno, Gem Identification Made Easy . Gemstone Press
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