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Cassidyite

A valid IMA mineral species
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00236990017271921871263.jpg
Will Cassidy
Formula:
Ca2Ni(PO4)2 · 2H2O
Ni may be replaced by minor Mg.
Colour:
Pale green to bright green.
Hardness:
3½
Specific Gravity:
3.15 (Calculated)
Crystal System:
Triclinic
Name:
Named by J.S. White, E.P. Henderson, and B. Mason in 1967 in honor of William A. Cassidy (3 January 1928 – 22 March 2020) geologist and professor of Geology and Planetary Science at the University of Pittsburgh. He recognized that Antarctica was the greatest repository of meteorites on earth and mapped the Wolf Creek crater in 1953. Cassidy Glacier in Antarctica is also named after him.

Compare lisanite and shasuite; and yakubovichite.


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Unique IdentifiersHide

Mindat ID:
916
Long-form identifier:
mindat:1:1:916:8

IMA Classification of CassidyiteHide

Classification of CassidyiteHide

Strunz-mindat (2025):
8.CG.05

8 : PHOSPHATES, ARSENATES, VANADATES
C : Phosphates without additional anions, with H2O
G : With large and medium-sized cations, RO4:H2O = 1:1
Dana 8th ed.:
40.2.2.4

40 : HYDRATED NORMAL PHOSPHATES,ARSENATES AND VANADATES
2 : AB2(XO4)2·xH2O
Hey's CIM Ref.:
19.15.2

19 : Phosphates
15 : Phosphates of Ni

Mineral SymbolsHide

As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.

SymbolSourceReference
CdyIMA–CNMNCWarr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43

Pronunciation of CassidyiteHide

Pronunciation:
PlayRecorded byCountry
Jolyon RalphUnited Kingdom

Physical Properties of CassidyiteHide

Transparency:
Translucent
Colour:
Pale green to bright green.
Hardness:
3½ on Mohs scale
Density:
3.15(5) g/cm3 (Calculated)

Optical Data of CassidyiteHide

Type:
Biaxial
RI values:
nα = 1.64 - 1.65 nγ = 1.67
Max. Birefringence:
δ = 0.020 - 0.030
Based on recorded range of RI values above.

Interference Colours:
The colours simulate birefringence patterns seen in thin section under crossed polars. They do not take into account mineral colouration or opacity.

Michel-Levy Bar The default colours simulate the birefringence range for a 30 µm thin-section thickness. Adjust the slider to simulate a different thickness.

Grain Simulation You can rotate the grain simulation to show how this range might look as you rotated a sample under crossed polars.

Surface Relief:
Moderate
Dispersion:
relatively strong

Chemistry of CassidyiteHide

Mindat Formula:
Ca2Ni(PO4)2 · 2H2O

Ni may be replaced by minor Mg.
Element Weights:
Element% weight
O43.855 %
Ca21.971 %
P16.980 %
Ni16.088 %
H1.105 %

Calculated from ideal end-member formula.
Elements listed:
Ca, H, Ni, O, P - search for minerals with similar chemistry

Crystallography of CassidyiteHide

Crystal System:
Triclinic
Cell Parameters:
a = 5.71 Å, b = 6.73 Å, c = 5.41 Å
α = 96.83°, β = 107.37°, γ = 104.58°
Ratio:
a:b:c = 0.848 : 1 : 0.804
Unit Cell V:
187.74 ų (Calculated from Unit Cell)
Z:
1
Comment:
Point Group: 1 or 1.; Space Group: P-1 or P1

X-Ray Powder DiffractionHide

Geological EnvironmentHide

Paragenetic Mode(s):
Paragenetic ModeEarliest Age (Ga)
Stage 7: Great Oxidation Event<2.4
47i : [Terrestrial weathering of meteorites]

Type Occurrence of CassidyiteHide

Type Locality:
ⓘ Wolfe Creek meteorite crater, Carranya Station, Halls Creek Shire, Western Australia, Australia
General Appearance of Type Material:
Thin crusts and small spherules.
Place of Conservation of Type Material:
National Museum of Natural History, Washington, D.C., USA, 119553, 119554A.
Geological Setting of Type Material:
Cavities and cracks in a weathered meteorite
Associated Minerals at Type Locality:
ApatiteGoethiteJarositeLipscombiteReevesite
Reference:
White, John S., Henderson, E. P., Mason, and Brian (1967) Secondary minerals produced by weathering of the Wolf Creek meteorite. American Mineralogist, 52 (7-8) 1190-1197

Synonyms of CassidyiteHide

Other Language Names for CassidyiteHide

Relationship of Cassidyite to other SpeciesHide

Member of:
Collinsite Group > Kröhnkite Supergroup
Other Members of Collinsite Group:
AnorthoroseliteCa2Co(AsO4)2 · 2H2OTric.
CollinsiteCa2Mg(PO4)2 · 2H2OTric. 1 : P1
GaititeCa2Zn(AsO4)2 · 2H2OTric. 1 : P1
HilliteCa2Zn(PO4)2 · 2H2OTric. 1 : P1
NickeltalmessiteCa2Ni(AsO4)2 · 2H2OTric. 1 : P1
ParabrandtiteCa2Mn2+(AsO4)2 · 2H2OTric. 1 : P1
TalmessiteCa2Mg(AsO4)2 · 2H2OTric. 1 : P1
Unnamed (Fe2+-analogue of Parabrandtite)Ca2Fe2+(AsO4)2 · 2H2O

Related Minerals - Strunz-mindat GroupingHide

8.CG.FluckiteCaMn2+(AsO3OH)2 · 2H2OTric. 1 : P1
8.CG.DondoelliteCa2Fe(PO4)2 · 2H2OTric. 1 : P1
8.CG.Ca-HuréauliteCaMn5(PO4)4 · 4H2O
8.CG.AlumolukrahniteCa[CuAl](AsO4)2(H2O,OH)2Tric. 1 : P1
8.CG.05ParabrandtiteCa2Mn2+(AsO4)2 · 2H2OTric. 1 : P1
8.CG.05TalmessiteCa2Mg(AsO4)2 · 2H2OTric. 1 : P1
8.CG.05CollinsiteCa2Mg(PO4)2 · 2H2OTric. 1 : P1
8.CG.05MesseliteCa2Fe2+(PO4)2 · 2H2OTric. 1 : P1
8.CG.05GaititeCa2Zn(AsO4)2 · 2H2OTric. 1 : P1
8.CG.05AnorthoroseliteCa2Co(AsO4)2 · 2H2OTric.
8.CG.05FairfielditeCa2Mn2+(PO4)2 · 2H2OTric. 1 : P1
8.CG.05HilliteCa2Zn(PO4)2 · 2H2OTric. 1 : P1
8.CG.05Unnamed (Fe2+-analogue of Parabrandtite)Ca2Fe2+(AsO4)2 · 2H2O
8.CG.10ZincroseliteCa2Zn(AsO4)2 · 2H2OMon. 2/m : P21/b
8.CG.10RoseliteCa2Co(AsO4)2 · 2H2OMon. 2/m : P21/b
8.CG.10RruffiteCa2Cu(AsO4)2 · 2H2OMon. 2/m : P21/b
8.CG.10WendwilsoniteCa2Mg(AsO4)2 · 2H2OMon. 2/m : P21/b
8.CG.10BrandtiteCa2Mn2+(AsO4)2 · 2H2OMon. 2/m : P21/b
8.CG.10Unnamed (Fe2+-analogue of Brandtite)Ca2Fe2+(AsO4)2 · 2H2O
8.CG.15MawbyitePbFe3+2(AsO4)2(OH)2Mon. 2/m : B2/m
8.CG.15ThometzekitePbCu2+2(AsO4)2 · 2H2OMon. 2/m : B2/m
8.CG.15YancowinnaitePbCuAl(AsO4)2OH · H2O Tric. 1 : P1
8.CG.15SchneebergiteBiCo2(AsO4)2(OH) · H2OMon. 2/m : B2/m
8.CG.15CabalzariteCaMg2(AsO4)2 · 2H2OMon. 2/m : B2/m
8.CG.15NickelschneebergiteBiNi2(AsO4)2(OH) · H2OMon. 2/m : B2/m
8.CG.15LotharmeyeriteCaZn2(AsO4)2 · 2H2OMon. 2/m : B2/m
8.CG.15NickeltsumcoritePb(Ni,Fe3+)2(AsO4)2(H2O,OH)2Mon. 2/m : B2/m
8.CG.15MagnesiofluckiteCaMg(AsO3OH)2(H2O)2Tric. 1 : P1
8.CG.15KrettnichitePbMn3+2(VO4)2(OH)2Mon. 2/m : B2/m
8.CG.15CobalttsumcoritePbCo2(AsO4)2 · 2H2OMon. 2/m : B2/m
8.CG.15ManganlotharmeyeriteCaMn3+2(AsO4)2(OH)2Mon. 2/m : B2/m
8.CG.15TsumcoritePbZn2(AsO4)2 · 2H2OMon. 2/m : B2/m
8.CG.15FerrilotharmeyeriteCaZnFe3+(AsO4)2(OH) · H2OMon. 2/m : B2/m
8.CG.15CobaltlotharmeyeriteCaCo2(AsO4)2 · 2H2OMon. 2/m : B2/m
8.CG.15MounanaitePbFe3+2(VO4)2(OH)2Mon. 2/m : B2/m
8.CG.15NickellotharmeyeriteCaNi2(AsO4)2 · 2H2OMon. 2/m : B2/m
8.CG.20LukrahniteCaCuFe3+(AsO4)2(OH,H2O)2Tric. 1 : P1
8.CG.20HelmutwinkleritePbZn2(AsO4)2 · 2H2OTric. 1 : P1
8.CG.20PhosphogartrellitePbCuFe3+(PO4)2(OH,H2O)2Tric. 1 : P1
8.CG.20GartrellitePbCuFe3+(AsO4)2(OH) · H2OTric. 1 : P1
8.CG.20ZincgartrellitePbZn2(AsO4)2(H2O,OH)2Tric. 1 : P1
8.CG.20RappolditePbCo2(AsO4)2 · 2H2OTric. 1 : P1
8.CG.25Pottsite(Pb3xBi4-2x)(VO4)4 · H2O (0.8 < x < 1.0)Tet. 4/m : I41/a
8.CG.25Armellinoite-(Ce)Ca4Ce4+(AsO4)4 · H2OTet. 4/m : I41/a
8.CG.35NickeltalmessiteCa2Ni(AsO4)2 · 2H2OTric. 1 : P1
8.CG.55IrhtemiteCa4Mg(AsO4)2(HAsO4)2 · 4H2OMon.

Other InformationHide

Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

Internet Links for CassidyiteHide

References for CassidyiteHide

Localities for CassidyiteHide

This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.

Locality ListHide

- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for references and further information on this occurrence. ? - Indicates mineral may be doubtful at this locality. - Good crystals or important locality for species. - World class for species or very significant. (TL) - Type Locality for a valid mineral species. (FRL) - First Recorded Locality for everything else (eg varieties). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (e.g. from pseudomorphs).

All localities listed without proper references should be considered as questionable.
Australia (TL)
 
  • Western Australia
    • Halls Creek Shire
      • Carranya Station
White et al. (1967) +1 other reference
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