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 % P2 O5
Hydrogen 1.13 % H 10.11 % H2 O
Oxygen 44.91 % O
______ ______
100.00 % 100.00 % = TOTAL OXIDE
Empirical Formula:
Ca2 Ni0.75 Mg0.25 (PO4 )2 •2(H2 O)
Environment:
Alteration product of a highly weathered iron-nickel meteorite, formed by alteration of schreibersite.
IMA Status:
Approved IMA 1967
Locality:
Wolf Creek meteorite. Link to MinDat.org Location Data.
Name Origin:
Named for William A. Cassidy, who mapped the Wolf Creek, Australia, crater in 1953.
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 - Pinacoidal H-M Symbol ( 1 ) Space Group: P1
X Ray Diffraction:
By Intensity(I/Io ): 2.7(1), 3.03(0.95), 2.67(0.79),
Physical Properties of Cassidyite
Color:
Green, Light green.
Density:
3.1
Diaphaneity:
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 = -0.01 (Superior) - where the CI = (1-KPDcalc /KC )
KPDcalc = 0.2087,KPDmeas = 0.2121,KC = 0.2068 Ncalc = 1.64 - 1.65
Optical Data:
Biaxial (?), a=1.64-1.65, g=1.67, bire=0.0200-0.0300
Calculated Properties of Cassidyite
Electron Density:
Bulk Density (Electron Density)=3.15 gm/cc note: Specific Gravity of Cassidyite =3.15 gm/cc.
Fermion Index:
Fermion Index = 0.00362311 Boson Index = 0.99637689
Photoelectric:
PECassidyite = 8.45 barns/electronU=PECassidyite x r Electron Density= 26.59 barns/cc.
Radioactivity:
GRapi = 0 (Gamma Ray American Petroleum Institute Units) Cassidyite is Not Radioactive
Cassidyite Classification
Dana Class:
40.02.02.04 (40) Hydrated Phosphates, etc
(40.02) where A++ (B++)2 (XO4) � x(H2O)
(40.02.02) Fairfieldite Subgroup (Triclinic: P-1�)
40.02.02.01 Fairfieldite Ca2(Mn,Fe)(PO4)2•2(H2O) P1 1
40.02.02.02 Messelite Ca2(Fe,Mn)(PO4)2•2(H2O) P1 1
40.02.02.03 Collinsite Ca2(Mg,Fe)(PO4)2•2(H2O) P1 1
40.02.02.04 Cassidyite Ca2(Ni,Mg)(PO4)2•2(H2O) P1 1
40.02.02.05 Talmessite Ca2Mg(AsO4)2•2(H2O) P1 1
40.02.02.06 Gaitite Ca2Zn(AsO4)2•2(H2O) P1 1
40.02.02.07 Roselite-beta Ca2(Co,Mg)(AsO4)2•2(H2O) P 1 or P1 Tri
40.02.02.08 Parabrandtite Ca2Mn(AsO4)•2(H2O) P1,P 1 Tri
40.02.02.09 Hillite ! Ca2(Zn,Mg)[PO4]2•2(H2O) P1 1
40.02.02.10 Nickeltalmessite ! Ca2Ni(AsO4)2•2H2O P 1
Strunz Class:
08.CG.05 08 - PHOSPHATES, ARSENATES, VANADATES
08.C - Phosphates without Additional Anions, with H2O
08.CG -With large and medium-sized cations, RO4:H2O = 1:1
08.CG.05 Collinsite Ca2(Mg,Fe)(PO4)2•2(H2O) P1 1
08.CG.05 Gaitite Ca2Zn(AsO4)2•2(H2O) P1 1
08.CG.05 Cassidyite Ca2(Ni,Mg)(PO4)2•2(H2O) P1 1
08.CG.05 Fairfieldite Ca2(Mn,Fe)(PO4)2•2(H2O) P1 1
08.CG.05 Messelite Ca2(Fe,Mn)(PO4)2•2(H2O) P1 1
08.CG.05 Parabrandtite Ca2Mn(AsO4)•2(H2O) P1,P 1 Tri
08.CG.05 Uranophane-beta Ca[(UO2)SiO3(OH)]2•(H2O) P 21 /a 2/m
08.CG.05 Talmessite Ca2Mg(AsO4)2•2(H2O) P1 1
08.CG.05 Hillite ! Ca2(Zn,Mg)[PO4]2•2(H2O) P1 1
Other Cassidyite Information
References:
NAME( AntBidBlaNic4) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)
See Also:
Links to other databases for Cassidyite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - EUROmin Project
4 - Ecole des Mines de Paris
5 - GeoScienceWorld
6 - Google Images
7 - Google Scholar
8 - Handbook of Mineralogy (MinSocAm)
9 - Handbook of Mineralogy (UofA)
10 - MinDAT
11 - Mineralienatlas (Deutsch)
12 - Online Mineral Museum
13 - QUT Mineral Atlas
14 - Ruff.Info
15 - WWW-MINCRYST
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Cassidyite
Ca2(Ni,Mg)(PO4)2•2(H2O)
Dana No: 40.02.02.04 Strunz No: 08.CG.05
Locality:
Notes:
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