hexagonal Phosphates
Apatite
Ca5(PO4)3(F,Cl,OH)
Crystal Structure
#! Species: Apatite
#! System: Hexagonal (6/mmm)
#! Habit: Hexagonal prism with dipyramid and pinacoid
hexagonal[6/mmm]:{10-10}@1.0 + {10-11}@0.8 + {0001}@0.5
hexagonal
6/mmm
{10-10} {10-11} {0001}
Quick Facts
Hardness
5.0
Specific Gravity
3.16
Refractive Index
1.628
Optical Character
Uniaxial -
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Open in PlaygroundPhysical Properties
Crystal Systemhexagonal
Hardness (Mohs)5.0
Specific Gravity3.16
CleavagePoor {0001}
FractureConchoidal to uneven
LustreVitreous to subresinous
Optical Properties
Refractive Index1.628
Birefringence0.002-0.008
Optical CharacterUniaxial -
Dispersion0.013
Pleochroismweak: Body color / Lighter/paler shade (Best seen in blue and green varieties; neon blue shows blue/colorless)
FluorescenceVariable; yellow, orange, or blue depending on activator
Colours
Blue (neon, Paraiba-like)GreenYellowVioletPinkColourless
Localities
Brazil (Paraiba blue-green)Madagascar (neon blue)Mexico (yellow)Morocco (tabular)MyanmarTanzania
Common Inclusions
Liquid-filled tubesHealed fracturesCrystals
Known Treatments
Heat treatment (improves colour)
Crystal Forms
hexagonal_prismdipyramidpinacoid
Diagnostic Features
Hexagonal crystals; moderate hardness (5); wide range of fluorescence colours
Notes
Called the deceiver stone because its colours and properties mimic tourmaline, topaz, and other gems
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Open in PlaygroundRelated Minerals
Other minerals in the hexagonal system
