Pyrophosphite Mineral Data

General Pyrophosphite Information

Chemical Formula:

K2CaP2O7

Composition:

Molecular Weight = 287.36 gm

Potassium 24.35 % K 29.34 % K₂O

Sodium 0.80 % Na 1.08 % Na₂O

Calcium 13.81 % Ca 19.32 % CaO

Magnesium 0.51 % Mg 0.84 % MgO

Phosphorus 21.56 % P 49.40 % P₂O₅

Oxygen 38.97 % O

______ ______

100.00 % 99.97 % = TOTAL OXIDE

Empirical Formula:

K_1.79Na_0.1Ca_0.99Mg_0.06P₂O₇

Environment:

Arnhemite and pyrophosphite are the principal phases in a slag that forms a thin layer in a profile of cave soil. The slag is interpreted to have resulted from the melting of ashes during the combustion of bat quano.

IMA Status:

Not Approved IMA

Locality:

Arhem Cave, 150 km east of Windhoek, Namibia. Link to MinDat.org Location Data.

Name Origin:

Named after the Greek pyros, meaning fire and the element name - Phosphorus.

Pyrophosphite Crystallography

Axial Ratios:

a:b:c =1.7233:1:2.2917

Cell Dimensions:

a = 9.742, b = 5.653, c = 12.955, Z = 4; beta = 104.35° V = 691.19 Den(Calc)= 2.76

Crystal System:

Monoclinic - Prismatic H-M Symbol (2/m) Space Group: P 2₁/n

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

By Intensity(I/I_o): 2.821(1), 2.987(0.64), 3.137(0.33),

Physical Properties of Pyrophosphite

Cleavage:

None

Color:

White.

Density:

2.75 - 2.76, Average = 2.75

Diaphaneity:

Transparent

Fracture:

Friable - The crumbly disintegration of earthy materials or highly fractured minerals.

Habit:

Anhedral Grains - Granular minerals without the expression of crystal shapes

Habit:

Microscopic Crystals - Crystals visible only with microscopes.

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Pyrophosphite

Gladstone-Dale:

CI meas= -0.031 (Excellent) - where the CI = (1-KPDmeas/KC)
CI calc= -0.029 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.1978,KPDmeas= 0.1982,KC= 0.1922
Ncalc = 1.53

Optical Data:

Biaxial (?), a=1.543, g=1.549, bire=0.0060

Calculated Properties of Pyrophosphite

Electron Density:

Bulk Density (Electron Density)=2.72 gm/cc
note: Specific Gravity of Pyrophosphite =2.76 gm/cc.

Fermion Index:

Fermion Index = 0.0009101723
Boson Index = 0.9990898277

Photoelectric:

PE_{Pyrophosphite}= 5.20 barns/electron
U=PE_{Pyrophosphite} x r_electron= 14.15 barns/cc.

Radioactivity:

GRapi = 346.36 (Gamma Ray American Petroleum Institute Units)
Concentration of Pyrophosphite per GRapi unit = 0.29 (%)

Estimated Radioactivity from Pyrophosphite - barely detectable

Pyrophosphite Classification

Dana Class:

37.00.00.00 (37)Phosphate Minerals

(37.00)Without Dana Classification Numbers

(37.00.00)Phosphate, Thermocaca Series

37.00.00.00 Arnhemite* (K,Na)2Mg2(P2O7)•5(H2O) Unk Hex

37.00.00.00 Arsenowaylandite* BiAl3(AsO4)2(OH)6 R 3m 3 2/m

37.00.00.00 Auroantimonate* AuSbO3 Ortho ? Ortho

37.00.00.00 Barium-zinc-alumopharmacosiderite* (Ba,K)0.5(Zn,Cu)0.5(Al,Fe)4(AsO4)3•5(H2O) I 42m 4 2m

37.00.00.00 Chernovite-(Ce)* (Ce,Y)(AsO4) I 4₁/amd 4/m 2/m 2/m

37.00.00.00 Churchite-(Dy)* (Dy,Sm,Gd,Nd)(PO4)•2(H2O) Mono

37.00.00.00 Gengenbachite KFe3(H2PO4)2(HPO4)4•6H2OorKFe3H8(PO4)6•6H2O P 6₃mc 6mm

37.00.00.00 IMA2008-063 Pb[Zn0.25,[]0.75]Fe3H(AsO4)2(OH)6 C 2/c 2/m

37.00.00.00 IMA2009-005 (Y,Ca,REE)5[(Si,P)O4]3F P 6₃/m 6/m 2/m 2/m

37.00.00.00 IMA2009-016 Cu4H(AsO4)2(OH)3•H2O P1 1

37.00.00.00 Kerstenite? PbSeO4(?) P nma 2/m 2/m 2/m

37.00.00.00 Krasnoselskite* CoWO4 P 2/c 2/m

37.00.00.00 Laubmannite? Fe3Fe6(PO4)4(OH)12 Unk Ortho

37.00.00.00 Oxiberaunite* (Fe,Mn)Fe5(PO4)4O(OH)4•6(H2O) Mono

37.00.00.00 Parwanite (Na,K)(Mg,Ca)4Al8(PO4)8(CO3)(OH)7•30H2O P 2, Pm, P 2/m, P 2₁, Mono

37.00.00.00 Pyrocoproite* (Mg(K,Na))2P2O7 Unk Mono

37.00.00.00 Pyrophosphite* K2CaP2O7 P 2₁/n 2/m

37.00.00.00 Zinclavendulan? NaCa(Zn,Cu)5(AsO4)4Cl•4-5(H2O) Unk Ortho

Strunz Class:

08.FA.20 08 - PHOSPHATES, ARSENATES, VANADATES

08.F - Polyphosphates, Polyarsenates, [4]-Polyvanadates

08.FA -Polyphosphates, etc., without OH and H2O; dimers of corner-sharing RO4 tetrahedra.

08.FA.20 Pyrocoproite* (Mg(K,Na))2P2O7 Unk Mono

08.FA.20 Pyrophosphite* K2CaP2O7 P 2₁/n 2/m

Other Pyrophosphite Information

References:

NAME( AmMin, v84:193) PHYS. PROP.(Am.Min.,Vol.84,p193,1999) OPTIC PROP.(Am.Min.,Vol.84,p193,1999)

See Also:

Links to other databases for Pyrophosphite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - GeoScienceWorld
4 - Google Images
5 - Google Scholar
6 - MinDAT
7 - Mineralienatlas (Deutsch)
8 - Online Mineral Museum
9 - QUT Mineral Atlas
10 - Ruff.Info

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Pyrophosphite

K2CaP2O7
Dana No: 37.00.00.00 Strunz No: 08.FA.20
Locality:

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