Apatite series

Formula:  Ca5(PO4,CO3)3(F,Cl,OH)

 

Origin of name:  From Greek apate = deceit

 

Crystal system:  Hexagonal

Crystal class:  6/m

Twinning:

Unit cell:

 

Colour:  Colourless, white, gray, yellow to yellowish green, green, blue, violet, red, brown

Diaphaneity:  Transparent to opaque

Luster:  Vitreous to subresinous, silky greasy

Habit:  Crystals short to long prismatic, thin to thick tabular or complex; massive compact to coarse granular; fibrous, globular, reniform, stalactitic

Hardness:  5

Specific gravity:  3.05 to 3.20

Cleavage:  2; {0001} indistinct; {10-10} trace

Tenacity:

Streak:  White

 

Synonyms/varieties:

 

Comments:  The apatite series has three end-members; fluorapatite, chlorapatite and hydroxylapatite.  There are two additional species in which carbonate partially replaces phosphate: carbonate-fluorapatite and carbonate-hydroxylapatite.

 

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