Lecontite Mineral Data

Lecontite Mineral Data +

General Lecontite Information

Chemical Formula:

(NH4,K)Na(SO4)·2(H2O)

Composition:

Molecular Weight = 178.39 gm

Potassium 5.48 % K 6.60 % K₂O

Sodium 12.89 % Na 17.37 % Na₂O

Hydrogen 1.70 % H - % Calc as (NH₄)₂O

Hydrogen 2.26 % H 20.20 % H₂O

Sulfur 17.98 % S 44.88 % SO₃

Nitrogen 5.89 % N 10.95 % (NH₄)₂O

Oxygen 53.81 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

(NH₄)_0.75K_0.25Na(SO₄)·2(H₂O)

IMA Status:

Valid Species (Pre-IMA) 1858

Locality:

Link to MinDat.org Location Data.

Synonym:

ICSD 77896

PDF 15-283

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Lecontite Crystallography

Axial Ratios:

a:b:c =0.6412:1:0.4856

Cell Dimensions:

a = 8.24, b = 12.85, c = 6.24, Z = 4; V = 660.72 Den(Calc)= 1.79

Crystal System:

Orthorhombic - DisphenoidalH-M Symbol (2 2 2) Space Group: P 2₁2₁2₁

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

By Intensity(I/I_o): 5.068(1), 3.802(0.94), 3.033(0.89),

Physical Properties of Lecontite

Cleavage:

[011] Distinct

Color:

Colorless.

Density:

1.745

Diaphaniety:

Transparent

Hardness:

2-2.5 - Gypsum-Finger Nail

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Lecontite

Gladstone-Dale:

CI meas= -0.328 (Poor) - where the CI = (1-KPDmeas/KC)
CI calc= -0.295 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2512,KPDmeas= 0.2577,KC= 0.1941

Optical Data:

Biaxial (-), a=1.44, b=1.454, g=1.455, bire=0.0150, 2V(Calc)=28, 2V(Meas)=29.74.

Calculated Properties of Lecontite

Electron Density:

r_electron=1.85 gm/cc
note: r_Lecontite=1.79 gm/cc.

Fermion Index

Fermion Index = 0.06029
Boson Index = 0.93971

Photoelectric:

PE_Lecontite= 1.87 barns/electron
U=PE_Lecontite x r_electron= 3.46 barns/cc.

Radioactivity:

GRapi = 81.53 (Gamma Ray American Petroleum Institute Units)

Estimated Radioactivity from Lecontite - barely detectable

Lecontite Classification

Dana Class:

29.2.1.1 (29)Hydrated Acid and Sulfates

(29.2)where (A+)2 XO4 · x(H2O)

(29.2.1)Dana Group

29.2.1.1 Lecontite (NH4,K)Na(SO4)·2(H2O) P 2₁2₁2₁ 2 2 2

Strunz Class:

VI/C.21-20 VI - Sulfates,Chromates,Molybdates and Tungstates

VI/C - Water-bearing sulfates without unfamiliar anions. Cations of very big size

VI/C.21 - Matteuccite - Mirabilite series

VI/C.21-10 Matteuccite NaHSO4·(H2O) Aa m

VI/C.21-20 Lecontite (NH4,K)Na(SO4)·2(H2O) P 2₁2₁2₁ 2 2 2

VI/C.21-30 Eugsterite Na4Ca(SO4)3·2(H2O) Unk. Mono

VI/C.21-40 Hydroglauberite Na4Ca(SO4)3·2(H2O) Unk. Ortho

VI/C.21-50 Wattevillite Na2Ca(SO4)2·4(H2O)(?) Unk Ortho

VI/C.21-60 Syngenite K2Ca(SO4)2·(H2O) P 2₁/m 2/m

VI/C.21-70 Koktaite (NH4)2Ca(SO4)2·(H2O) P 2₁/m 2/m

VI/C.21-80 Mirabilite Na2SO4·10(H2O) P 2₁/a 2/m

Other Lecontite Information

References:

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

See Also:

Links to other databases for Lecontite :
1 -Am. Min. Crystal Structure Database 2 -Athena 3 - EUROmin Project 4 -Google Images 5 -Google Scholar 6 -Handbook of Mineralogy (UofA) 7 -MinDAT 8 -MinMax(Deutsch) 9 -MinMax(English) 10 -Mineralienatlas (Deutsch) 11 -QUT Mineral Atlas 12 - WWW-MINCRYST 13 -École des Mines de Paris

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Lecontite

(NH4,K)Na(SO4)·2(H2O)
Dana No: 29.2.1.1 Strunz No: VI/C.21-20
Locality:

Notes: