Potassium-alum Mineral Data

Potassium-alum Mineral Data

General Potassium-alum Information

Chemical Formula:

KAl(SO4)2·12(H2O)

Composition:

Molecular Weight = 474.39 gm

Potassium 8.24 % K 9.93 % K₂O

Aluminum 5.69 % Al 10.75 % Al₂O₃

Hydrogen 5.10 % H 45.57 % H₂O

Sulfur 13.52 % S 33.75 % SO₃

Oxygen 67.45 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

KAl(SO₄)₂·12(H₂O)

Environment:

Derived from the oxidation of sulfide minerals and potassium-bearing minerals.

IMA Status:

Valid Species (Pre-IMA) 1875

Locality:

Vesuvius, Italy. Alum Cave, Tennessee, USA. Link to MinDat.org Location Data.

Name Origin:

Named for the element K and the Latin, alumen.

Synonym:

Native Alum

Potash Alum

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Potassium-alum Crystallography

Cell Dimensions:

a = 12.133, Z = 4; V = 1,786.10 Den(Calc)= 1.76

Crystal System:

Isometric - DiploidalH-M Symbol (2/m 3) Space Group: P a3

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

By Intensity(I/I_o): 4.298(1), 3.25(0.55), 4.053(0.45),

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Physical Properties of Potassium-alum

Cleavage:

[111] Indistinct

Color:

Colorless, White.

Density:

1.76

Diaphaniety:

Transparent

Fracture:

Conchoidal - Fractures developed in brittle materials characterized by smoothly curving surfaces, (e.g. quartz).

Habit:

Water Soluble - Water soluble mineral.

Hardness:

2 - Gypsum

Luminescence:

Non-fluorescent.

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Potassium-alum

Gladstone-Dale:

CI meas= -0.004 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= -0.004 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2574,KPDmeas= 0.2574,KC= 0.2564

Optical Data:

Isotropic, n=1.453.

Calculated Properties of Potassium-alum

Electron Density:

r_electron=1.84 gm/cc
note: r_{Potassium-alum}=1.76 gm/cc.

Fermion Index

Fermion Index = 0.00135
Boson Index = 0.99865

Photoelectric:

PE_{Potassium-alum}= 1.89 barns/electron
U=PE_{Potassium-alum} x r_electron= 3.47 barns/cc.

Radioactivity:

GRapi = 124.32 (Gamma Ray American Petroleum Institute Units)

Estimated Radioactivity from Potassium-alum - barely detectable

Potassium-alum Classification

Dana Class:

29.5.5.1 (29)Hydrated Acid and Sulfates

(29.5)where A B (XO4)2 · x(H2O)

(29.5.5)Alum Group

29.5.5.1 Potassium-alum KAl(SO4)2·12(H2O) P a3 2/m 3

29.5.5.2 Sodium-alum NaAl(SO4)2·12(H2O) P a3 2/m 3

29.5.5.3 Tschermigite (NH4)Al(SO4)2·12(H2O) P a3 2/m 3

29.5.5.4 Lonecreekite (NH4)(Fe,Al)(SO4)2·12(H2O) P a3 2/m 3

29.5.5.5 Lanmuchangite! TlAl(SO4)2·12(H2O) P a3 2/m 3

Strunz Class:

VI/C.14-20 VI - Sulfates,Chromates,Molybdates and Tungstates

VI/C - Water-bearing sulfates without unfamiliar anions. cations of medium and very big size

VI/C.14 - Sodium alum - Zincovoltaite series

VI/C.14-10 Sodium-alum NaAl(SO4)2·12(H2O) P a3 2/m 3

VI/C.14-20 Potassium-alum KAl(SO4)2·12(H2O) P a3 2/m 3

VI/C.14-30 Tschermigite (NH4)Al(SO4)2·12(H2O) P a3 2/m 3

VI/C.14-40 Lonecreekite (NH4)(Fe,Al)(SO4)2·12(H2O) P a3 2/m 3

VI/C.14-45 Lanmuchangite! TlAl(SO4)2·12(H2O) P a3 2/m 3

VI/C.14-50 Voltaite K2Fe5Fe3Al(SO4)12·18(H2O) F d3c 4/m 3 2/m

VI/C.14-60 Zincovoltaite K2Zn5Fe3Al(SO4)12·18(H2O) F d3c 4/m 3 2/m

Other Potassium-alum Information

References:

NAME( Dana7) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Dana7)

See Also:

Links to other databases for Potassium-alum :
1 -Am. Min. Crystal Structure Database 2 -Athena 3 -Google Images 4 -Google Scholar 5 -MinDAT 6 -MinMax(Deutsch) 7 -MinMax(English) 8 -Mineralienatlas (Deutsch) 9 -QUT Mineral Atlas

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Potassium-alum

KAl(SO4)2·12(H2O)
Dana No: 29.5.5.1 Strunz No: VI/C.14-20
Locality:

Notes: