Images
Formula: Ca5(PO4)3Cl
Anhydrous phosphate containing halogen, apatite group,
apatite supergroup
Crystal System: Hexagonal
Specific gravity: 3.17 to 3.18 measured, 3.17 calculated
Hardness: 5
Streak: White
Colour: White
Solubility: Soluble in hydrochloric acid or in nitric acid
Environments
Pegmatites
Metamorphic environments
Hydrothermal environments
Meteorites
Chlorapatite is relatively much rarer than fluorapatite or
hydroxylapatite, formed in F-deficient environments. In
calc-silicate
marble; an accessory mineral in layered
mafic intrusions; in veins through
dolerite; replacing
triphylite in granite
pegmatites; in meteorites
(HOM).
A monoclinic polymorph, chlorapatite-M is known.
Common associates include hornblende,
ilmenite, magnetite,
pyrrhotite, rutile,
scapolite and titanite
(Mindat).
Localities
At the Bobs Lake Chlorapatite occurrence, Oso Township, Frontenac County, Ontario, Canada, the area of
chlorapatite occurrence consists mainly of granites,
granitic gneisses and
gneissic
granodiorites with some
anorthositic gabbros.
Interfingering with the granitic rocks are irregular bands of
amphibolite and
marble. Most of the skarn
deposits in the area are of the phlogopite -
fluorapatite type occasionally with considerable quantities of
scapolite.
The chlorapatite at Bob's Lake occurs in
calc-silicate
marble as a thin vein. The
apatite is associated with
actinolite, diopside and
lesser amounts of calcite, quartz
and talc. The vein minerals with the exception of the chlorapatite
also occur in the surrounding marble.
Mica and scapolite are noticeably
absent. Talc coats much of the
actinolite and occurs as inclusions in the
calcite and apatite. In some
cases the calcite has weathered to a rhombohedral framework of
talc.
In general the chlorapatite crystals are pinkish-white and have a chalky lustre due to the included
talc, some crystals observed have a thin chalky coating and transparent cores.
Completely transparent, pale yellow crystals have also been found but these are not very common
(CM 10.252–259).
At the Angarf-South pegmatite, Ouisselsate Caïdat, Amerzgane Cercle, Ouarzazate Province, Drâa-Tafilalet Region,
Morocco, chlorapatite is associated with olivine,
orthopyroxene, phlogopite,
ferroalluaudite and
chromite
(HOM).
There are two co-type localities, Kragerø, Vestfold og Telemark, Norway and Diksberg, Ransäter, Munkfors, Värmland
County, Sweden.
At the type localities chlorapatite occurs as white hexagonal crystals associated with
titanite, rutile,
ilmenite, calcite and
albite
(Mindat).
At the Fairfax quarry, Centreville, Culpeper Basin, Fairfax county, Virginia, USA,
apatite group crystals are zoned with the crystal cores consisting of
translucent light greenish-grey chlorapatite and opaque white alteration zones of
fluorapatite along the crystal margins and internal fractures.
A paragenetic sequence is suggested in which, after precipitation of chlorapatite and
diopside along a joint in the
dolerite, the host rock and the chlorapatite crystals were
fractured and then altered by a fluorine-containing solution that partially replaced the chlorine, thus producing
the zoned crystals.
(R&M 98.2.126).
At the Bull Run Quarry, Conklin, Loudoun county, Virginia, USA, chlorapatite is associated with
amphibole, chlorite,
plagioclase, titanite and
datolite
(HOM).
Back to Minerals