Mineral phase
IMA name
Crandallite
Type
Class
non-silicate mineral
Compound type
phosphate
Chemical composition
Formula
$CaAl_3(PO_4)_2(OH)_5 \bullet (H_2O)$
Chemical formula
CaAl3(PO4)2(OH)5•(H2O)
Elemental formula
Ca Al3 P2 O3 (O-)11 H7
Isotope mixture type
terrestrial abundance
  Formula Name Family Number min-max Isotope mole fraction State Relevance
$Ca$ Calcium element 1 constituent element main
$Al$ Aluminium element 3 constituent element main
$(PO_4)^{3-}$ Phosphate anion chemical function 2 anionic radical main
$(OH)^-$ Hydroxide anion chemical function 5 anionic radical main
$H_2O$ Water molecule 1 hydration main
Chemical functions
  Function Number
$(PO_4)^{3-}$ 2
$R-OH$ 2
Chemical bonds
  Bond Number
$-O-H$ 2
$\dddot - \dddot - \dddot - P \dddot - O^{-3/4}$ 4
Oxides
Formula $CaO$ $Al_{2}O_{3}$ $P_{2}O_{5}$ $H_{2}O$
Mass fraction (%) 13.54 36.94 34.28 15.23

Strunz

Class
phosphates - arsenates - vanadates (08)
Division
phosphates, etc. with additional anions, without H2O (08.B)
Family
with medium-sized and large cations, (OH, etc.):RO4 = 3:1 (08.BL)
Code
08.BL.10

Dana

Major class
phosphates, arsenates, vanadates (VII)
Class
hydrated phosphates containing hydroxyl or halogen (42)
Type
where (AB)2 (XO4) Zq·x(H2O) (42.07)
Group
Crandallite group (42.07.03)
Code
42.07.03.01
Phase type
crystalline
Crystal system
trigonal
Crystal class
ditrigonal-scalenohedral
Crystal class symbol
-3m (D3d)
Crystal spacegroup
R-3m
Molar mass
414.02 $g/mol$
Density
2.78-2.92 $g/cm^3$
State NTP
solid
Refringence type
uniaxial
Refringence sign
positive
Birefringence
0.005
Refraction index $n_o$ (w)
1.618
Refraction index $n_e$ (e)
1.623
Pure color
white
Color
gray, yellow, yellowish white, light red
Diaphaneity
transparent to subtranslucent
Luster
vitreous
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