Cassidyite Mineral Data

Cassidyite Mineral Data

General Cassidyite Information

Chemical Formula:

Ca2(Ni,Mg)(PO4)2·2(H2O)

Composition:

Molecular Weight = 356.22 gm

Calcium 22.50 % Ca 31.48 % CaO

Magnesium 1.71 % Mg 2.83 % MgO

Nickel 12.36 % Ni 15.73 % NiO

Phosphorus 17.39 % P 39.85 % P₂O₅

Hydrogen 1.13 % H 10.11 % H₂O

Oxygen 44.91 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Ca₂Ni_0.75Mg_0.25(PO₄)₂·2(H₂O)

IMA Status:

Approved IMA 1967

Locality:

Link to MinDat.org Location Data.

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Cassidyite Crystallography

Axial Ratios:

a:b:c =0.8484:1:0.8038

Cell Dimensions:

a = 5.71, b = 6.73, c = 5.41, Z = 1; alpha = 96.83°, beta = 107.4°, gamma = 104.6° V = 190.62 Den(Calc)= 3.10

Crystal System:

Triclinic - PinacoidalH-M Symbol ( 1) Space Group: P1

$Help on X Ray Diffraction:$ X Ray Diffraction:

By Intensity(I/I_o): 2.7(1), 3.03(0.95), 2.67(0.79),

Physical Properties of Cassidyite

Color:

Green, Light green.

Density:

3.1

Diaphaniety:

Transparent

Hardness:

3.5 - Copper Penny

Luster:

Vitreous (Glassy)

Optical Properties of Cassidyite

Gladstone-Dale:

CI meas= -0.026 (Excellent) - where the CI = (1-KPDmeas/KC)
CI calc= -0.026 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2121,KPDmeas= 0.2121,KC= 0.2068

Optical Data:

Biaxial (?), a=1.64-1.65, g=1.67, bire=0.0200-0.0300

Calculated Properties of Cassidyite

Electron Density:

r_electron=3.10 gm/cc
note: r_Cassidyite=3.10 gm/cc.

Fermion Index

Fermion Index = 0.00362
Boson Index = 0.99638

Photoelectric:

PE_Cassidyite= 8.45 barns/electron
U=PE_Cassidyite x r_electron= 26.17 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Cassidyite is Not Radioactive

Cassidyite Classification

Dana Class:

40.2.2.4 (40)Hydrated Phosphates, etc

(40.2)where A++ (B++)2 (XO4) · x(H2O)

(40.2.2)Fairfieldite Subgroup (Triclinic: P1¯)

40.2.2.1 Fairfieldite Ca2(Mn,Fe)(PO4)2·2(H2O) P1 1

40.2.2.2 Messelite Ca2(Fe,Mn)(PO4)2·2(H2O) P1 1

40.2.2.3 Collinsite Ca2(Mg,Fe)(PO4)2·2(H2O) P1 1

40.2.2.4 Cassidyite Ca2(Ni,Mg)(PO4)2·2(H2O) P1 1

40.2.2.5 Talmessite Ca2Mg(AsO4)2·2(H2O) P1 1

40.2.2.6 Gaitite Ca2Zn(AsO4)2·2(H2O) P1 1

40.2.2.7 Roselite-beta Ca2(Co,Mg)(AsO4)2·2(H2O) P 1 or P1 Tri

40.2.2.8 Parabrandtite Ca2Mn(AsO4)·2(H2O) P1,P 1 Tri

40.2.2.9 Hillite! Ca2(Zn,Mg)[PO4]2·2(H2O) P1 1

Strunz Class:

VII/C.17-40 VII - Phosphates, Arsenates and Vanadates

VII/C - Water-bearing phosphates without unfamiliar anions, cations of medium and big size: Fe, Mn, Zn, Mg and Ca, (NH4)1+

VII/C.17 - Collinsite - Wendwilsonite series

VII/C.17-10 Collinsite Ca2(Mg,Fe)(PO4)2·2(H2O) P1 1

VII/C.17-15 Hillite! Ca2(Zn,Mg)[PO4]2·2(H2O) P1 1

VII/C.17-20 Messelite Ca2(Fe,Mn)(PO4)2·2(H2O) P1 1

VII/C.17-30 Fairfieldite Ca2(Mn,Fe)(PO4)2·2(H2O) P1 1

VII/C.17-40 Cassidyite Ca2(Ni,Mg)(PO4)2·2(H2O) P1 1

VII/C.17-50 Talmessite Ca2Mg(AsO4)2·2(H2O) P1 1

VII/C.17-60 Gaitite Ca2Zn(AsO4)2·2(H2O) P1 1

VII/C.17-70 Parabrandtite Ca2Mn(AsO4)·2(H2O) P1,P 1 Tri

VII/C.17-80 Roselite-beta Ca2(Co,Mg)(AsO4)2·2(H2O) P 1 or P1 Tri

VII/C.17-90 Wendwilsonite Ca2(Mg,Co)(AsO4)2·2(H2O) P 2₁/c 2/m

VII/C.17-100 Roselite Ca2(Co,Mg)(AsO4)2·2(H2O) P 2₁/c 2/m

VII/C.17-110 Brandtite Ca2(Mn,Mg)(AsO4)2·2(H2O) P 2₁/c 2/m

VII/C.17-120 Zincroselite Ca2Zn(AsO4)2·2(H2O) P 2₁/c 2/m

Other Cassidyite Information

References:

PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)

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Cassidyite

Ca2(Ni,Mg)(PO4)2·2(H2O)
Dana No: 40.2.2.4 Strunz No: VII/C.17-40
Locality:

Notes: