There are three apatites:
Fluorapatite: Ca5(PO4)3F
Hydroxylapatite: Ca5(PO4)3(OH)
Chlorapatite: Ca5(PO4)3Cl
All of these are anhydrous phosphates containing hydroxyl or halogen, and they belong to the apatite group, apatite supergroup.
Fluorapatite is the commonest apatite.


Collophane is a carbonate-rich variety of apatite


Crystal System: Hexagonal
Specific gravity:
Fluorapatite: 3.1 to 3.25 measured, 3.18 calculated
Hydroxylapatite: 3.10 to 3.21 measured, 3.16 calculated
Chlorapatite: 3.17 to 3.18 measured, 3.17 calculated
Hardness: 5
Streak: White
Colour: Colourless to white, grey, also green, blue, pink, yellow, brown, violet, purple, red
Common impurities: OH,Cl,transition elements,La,Ce,Pr,Nd,Sm,Eu,Gd,Dy,Y,Er,Mn

Plutonic igneous environments
Sedimentary environments
Metamorphic environments
Hydrothermal environments

Apatite is a primary and secondary mineral, widely distributed with important concentrations in carbonatites. It is the most common rock-forming phosphate and a major mineral in lithified phosphate-rich sediments. It occurs the oxidation zone of hypothermal (high temperature) veins and in Alpine cleft-type veins.
It is a common secondary mineral in high-temperature hydrothermal alteration zones (AofA).

Apatite is a common constituent of marble, skarn and magnetite deposits.
It may also be found in quartzolite, granite, syenite, diorite, rhyolite, trachyte, andesite and basalt.

Apatite crystallises in the hexagonal system, point group 6/m. Crystals are common, tabular parallel to {0001} or short to long prismatic with {1010}, {1011} and minor {0001}, sometimes together with other prisms and bipyramids (OJ).


In the pegmatite at the Sapo mine, Minas Gerais, Brazil, apatite crystals are zoned, with a core of fluorapatite and an outer overgrowth of hydroxylapatite. They are associated with microcline, albite variety cleavelandite, quartz and muscovite (Min Rec 40.4.279-288).

The Ma On Shan Mine, Ma On Shan, Sha Tin District, New Territories, Hong Kong, China, is an abandoned iron mine, with both underground and open cast workings. The iron ores contain magnetite as the ore mineral and occur predominantly as masses of all sizes enclosed in a large skarn body formed by contact metasomatism of dolomitic limestone at the margins of a granite intrusion. In parts of the underground workings magnetite is also found in marble in contact with the granite. The skarn rocks consist mainly of tremolite, actinolite, diopside and garnet.
Apatite is found in the skarn rocks (Hong Kong Minerals (1991). Peng, C J. Hong Kong Urban Council)

At Nacozari, Mexico, turquoise pseudomorphs after apatite have been found (KL p211).

Apatite in Morocco is the most ubiquitous phosphate mineral and is found in most sedimentary, igneous and metamorphic settings. Well crystallized apatite, usually fluorapatite, occurs most frequently in igneous/hydrothermal rocks such as evolved gabbros and granitoids. It usually forms hexagonal, rectangular, acicular or rounded tiny grains with an average grain size of 0.1–0.2 mm, but it is also occasionally a main rock-forming mineral in some alkaline igneous systems (primarily those of Imilchil and Dakhla regions).
The major producing localities for apatites are connected with alkaline igneous intrusions. The apatite deposits form millimeter to centimetre thick veins hosted mainly by syenite rocks. The main components of these rocks are always alkali feldspars (mostly albite), pyroxene, amphibole, quartz, prehnite, calcite, magnetite, epidote and titanite.
The apatite crystals occur as hexagonal prisms that can reach 15 cm in length and 3 cm in width. Both fluorapatite and chlorapatite have been identified. The more abundant is fluorapatite formed in a white matrix, which consists of albite, K-feldspar, calcite, clinopyroxene, magnetite, prehnite and quartz. The most beautiful Moroccan gem-quality apatite is mined from this vein type, where the apatite is characterised by its perfect euhedral habit, green-yellow colour, transparency and glassy lustre.
Less common are chlorapatites, which are associated with veins of dark matrix consisting mainly of amphibole ±  prehnite; these are euhedral in habit, typically cloudy, pale green to grey, with variable lustre, and they frequently exhibit enclosed needles of amphibole.
Other significant Moroccan fluorapatite deposits are reported in Dakhla Gleibat Lafhouda-Twihinate carbonatite occurrences. These occur as euhedral to subhedral crystals that range in size from 0.2 to 2 mm. The most important concentrations are associated with iron oxide resting on top of the carbonatites. Coarse white to pale yellow apatite, as euhedral and subhedral crystals to 8 cm, comprising up to 40 volume percent of the rock, are hosted by these iron oxide rocks (R&M 98.2.172-173).

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