Phosphate minerals

Phosphate minerals are those minerals that contain the tetrahedrally coordinated phosphate (PO₄^3-) anion along with the freely substituting arsenate (AsO₄^3-) and vanadate (VO₄^3-). Chlorine (Cl^-), fluorine (F^-), and hydroxide (OH^-) anions also fit into the crystal structure.

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The phosphate class of minerals is a large and diverse group, however, only a few species are relatively common.

Examples include:

• triphylite Li(Fe,Mn)PO₄
• monazite (Ce,La,Y,Th)PO₄
• Apatite group Ca₅(PO₄)₃(F,Cl,OH)
  • hydroxylapatite Ca₅(PO₄)₃OH
  • fluorapatite Ca₅(PO₄)₃F
  • chlorapatite Ca₅(PO₄)₃Cl
• pyromorphite Pb₅(PO₄)₃Cl
• vanadinite Pb₅(VO₄)₃Cl
• erythrite Co₃(AsO₄)₂·8H₂O
• amblygonite LiAlPO₄F
• lazulite (Mg,Fe)Al₂(PO₄)₂(OH)₂
• wavellite Al₃(PO₄)₂(OH)₃·5H₂O
• turquoise CuAl₆(PO₄)₄(OH)₈·5H₂O
• autunite Ca(UO₂)₂(PO₄)₂·10-12H₂O
• carnotite K₂(UO₂)₂(VO₄)₂·3H₂O
• phosphophyllite Zn₂(Fe,Mn)(PO₄)₂•4H₂O

Applications

Phosphate minerals are often used for control of rust and prevention of corrosion on ferrous materials, applied with electrochemical conversion coatings.

See also

• Parkerizing

References

• Hurlbut, Cornelius S.; Klein, Cornelis, 1985, Manual of Mineralogy, 20th ed., John Wiley and Sons, New York ISBN 0-471-80580-7
• Webmineral - Strunz
• Webmineral - Dana