Delhayelite Mineral Data

Delhayelite Mineral Data +

General Delhayelite Information

Chemical Formula:

(Na,K)10Ca5Al6Si32O80(Cl2,F2,SO4)3·18(H2O)

Composition:

Molecular Weight = 3,231.17 gm

Potassium 3.03 % K 3.64 % K₂O

Sodium 5.34 % Na 7.19 % Na₂O

Calcium 6.20 % Ca 8.68 % CaO

Aluminum 5.01 % Al 9.47 % Al₂O₃

Silicon 27.81 % Si 59.50 % SiO₂

Hydrogen 1.12 % H 10.04 % H₂O

Sulfur 0.60 % S 1.49 % SO₃

Chlorine 0.77 % Cl 0.77 % Cl

- % Cl -0.17 % -O=Cl₂

Oxygen 49.71 % O

Fluorine 0.41 % F 0.41 % F

- % F -0.17 % -O=F₂

______ ______

100.00 % 100.84 % = TOTAL OXIDE

Empirical Formula:

Na_7.5K_2.5Ca₅Al₆Si₃₂O₈₀Cl_0.7F_0.7(SO₄)_0.6·18(H₂O)

Environment:

In a kalsilite-bearing melitlite-nepheline lava.

IMA Status:

Approved IMA 1959

Locality:

On Mt. Sharheru, the extinct southern cone of Mt. Nyiragongo, Kivu Province, Zaire. Link to MinDat.org Location Data.

Name Origin:

Named for Fernard Delhaye (1880-1946), Belgian geologist, a pioneer in the geological exploration of the northern Kivu region of Zaire.

Synonym:

ICSD 24616

PDF 12-286

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Delhayelite Crystallography

Axial Ratios:

a:b:c =0.5298:1:0.2855

Cell Dimensions:

a = 13.06, b = 24.65, c = 7.04, Z = 1; V = 2,266.38 Den(Calc)= 2.37

Crystal System:

Orthorhombic - DipyramidalH-M Symbol (2/m 2/m 2/m) Space Group: Pnmm

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

By Intensity(I/I_o): 3.078(1), 12.3(0.35), 6.158(0.25),

Physical Properties of Delhayelite

Cleavage:

[010] Distinct

Color:

Colorless, Greenish gray, Light gray green.

Density:

2.6

Diaphaniety:

Transparent

Habit:

Platy - Sheet forms (e.g. micas).

Hardness:

4-5 - Fluorite-Apatite

Streak:

white

Optical Properties of Delhayelite

Gladstone-Dale:

CI meas= 0.077 (Fair) - where the CI = (1-KPDmeas/KC)
CI calc= -0.012 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2245,KPDmeas= 0.2046,KC= 0.2218

Optical Data:

Biaxial (-), a=1.532, b=1.532, g=1.532, bire=0.0000, 2V(Calc)=0, 2V(Meas)=83.

Calculated Properties of Delhayelite

Electron Density:

r_electron=2.38 gm/cc
note: r_Delhayelite=2.37 gm/cc.

Fermion Index

Fermion Index = 0.01336
Boson Index = 0.98664

Photoelectric:

PE_Delhayelite= 2.46 barns/electron
U=PE_Delhayelite x r_electron= 5.85 barns/cc.

Radioactivity:

GRapi = 43.87 (Gamma Ray American Petroleum Institute Units)

Estimated Radioactivity from Delhayelite - barely detectable

Delhayelite Classification

Dana Class:

72.5.1.4 (72)Phyllosilicate Two-Dimensional Infinite Sheets with Other Than Six-Membered Rings

(72.5)with corrugated and complex layers

(72.5.1)Rhodesite group

72.5.1.1 Rhodesite KHCa2Si8O19·5(H2O) Pmam 2/m 2/m 2/m

72.5.1.2 Monteregianite-(Y) (Na,K)6(Y,Ca)2Si16O38·10(H2O) P 2₁/m 2/m

72.5.1.3 Macdonaldite BaCa4[Si16O36(OH)2]·10(H2O) C mcm 2/m 2/m 2/m

72.5.1.4 Delhayelite (Na,K)10Ca5Al6Si32O80(Cl2,F2,SO4)3·18(H2O) Pnmm 2/m 2/m 2/m

72.5.1.5 Hydrodelhayelite KCa2AlSi7O17(OH)2·6(H2O) Pnm21 mm2

72.5.1.6 Seidite-(Ce)! Na4(Ce,Sr)2{Ti(OH)2(Si8O18)}(O,OH,F)4·5(H2O) C/2c 2/m

Strunz Class:

VIII/H.38-30 VIII - Silicates

VIII/H - Phyllosilicates (layered) Mica minerals with tetrahedral-double layers and related structures

VIII/H.38 - Monteregianite-(Y) - Wickenburgite series

VIII/H.38-10 Monteregianite-(Y) (Na,K)6(Y,Ca)2Si16O38·10(H2O) P 2₁/m 2/m

VIII/H.38-20 Rhodesite KHCa2Si8O19·5(H2O) Pmam 2/m 2/m 2/m

VIII/H.38-30 Delhayelite (Na,K)10Ca5Al6Si32O80(Cl2,F2,SO4)3·18(H2O) Pnmm 2/m 2/m 2/m

VIII/H.38-40 Hydrodelhayelite KCa2AlSi7O17(OH)2·6(H2O) Pnm21 mm2

VIII/H.38-50 Macdonaldite BaCa4[Si16O36(OH)2]·10(H2O) C mcm 2/m 2/m 2/m

VIII/H.38-60 Cymrite BaAl2Si2O8·(H2O) P 2₁ (pseudo-HEX) 2

VIII/H.38-65 Kampfite! Ba6[(Si,Al)O2]8(CO3)2Cl2(Cl,H2O)2 P 6₃mmc, P 6₂c, P 6₃mc, P 3₁ Hex

VIII/H.38-80 Lourenswalsite (K,Ba)2(Ti,Mg,Ca,Fe)4(Si,Al,Fe)6O14(OH)12 Unk (pseudo-HEX) Hex

VIII/H.38-90 Wickenburgite Pb3CaAl2Si10O27·4(H2O) P 3₁c 3m

Other Delhayelite Information

References:

NAME( AntBidBlaNic2) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(AntBidBlaNic2)

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Delhayelite

(Na,K)10Ca5Al6Si32O80(Cl2,F2,SO4)3·18(H2O)
Dana No: 72.5.1.4 Strunz No: VIII/H.38-30
Locality:

Notes: