Mineralogy Database

Alum-(K) Mineral Data

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General Alum-(K) Information

Help on Chemical  Formula: Chemical Formula: KAl(SO4)2•12(H2O)
Help on Composition: 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
Help on Empirical Formula: Empirical Formula: KAl(SO4)2•12(H2O)
Help on Environment: Environment: Derived from the oxidation of sulfide minerals and potassium-bearing minerals.
Help on IMA Status: IMA Status: Valid Species (Pre-IMA) 1875
Help on Locality: Locality: Vesuvius, Italy. Alum Cave, Tennessee, USA. Link to MinDat.org Location Data.
Help on Name Origin: Name Origin: Named for the element K and the Latin, alumen.
Help on Synonym: Synonym: Native Alum
  Potash Alum
  Potassium-alum - Renamed to Alum-(K) by Mineralogical Record, v39 (2008), p131

Alum-(K) Image

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Comments: White encrustations and ballshaped aggregates of potassium alum.
Location: Scholler mine, Libusin, Kladno, Czech Republic. Scale: See Fingers for Scale.
© Diederik Visser

Alum-(K) Crystallography

Help on Cell Dimensions: Cell Dimensions: a = 12.133, Z = 4; V = 1,786.10 Den(Calc)= 1.76
Help on Crystal System: Crystal System: Isometric - Diploidal H-M Symbol (2/m 3) Space Group: P a3
Help on X Ray Diffraction: X Ray Diffraction: By Intensity(I/Io): 4.298(1), 3.25(0.55), 4.053(0.45),

Physical Properties of Alum-(K)

Help on Cleavage: Cleavage: {111} Indistinct
Help on Color: Color: Colorless, White.
Help on Density: Density: 1.76
Help on Diaphaneity: Diaphaneity: Transparent
Help on Fracture: Fracture: Conchoidal - Fractures developed in brittle materials characterized by smoothly curving surfaces, (e.g. quartz).
Help on Habit: Habit: Water Soluble - Water soluble mineral.
Help on Hardness: Hardness: 2 - Gypsum
Help on Luminescence: Luminescence: Non-fluorescent.
Help on Luster: Luster: Vitreous (Glassy)
Help on Streak: Streak: white

Optical Properties of Alum-(K)

Help on Gladstone-Dale: 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
Ncalc = 1.45
Help on Optical Data: Optical Data: Isotropic, n=1.453.

Calculated Properties of Alum-(K)

Help on Electron Density: Electron Density: Bulk Density (Electron Density)=1.84 gm/cc
note: Specific Gravity of Alum-(K) =1.76 gm/cc.
Help on Fermion Index: Fermion Index: Fermion Index = 0.0013552227
Boson Index = 0.9986447773
Help on Photoelectric: Photoelectric: PEAlum-(K) = 1.89 barns/electron
U=PEAlum-(K) x relectron= 3.47 barns/cc.
Help on Radioactivity: Radioactivity:

GRapi = 124.32 (Gamma Ray American Petroleum Institute Units)
Concentration of Alum-(K) per GRapi unit = 0.80 (%)

Estimated Radioactivity from Alum-(K) - barely detectable


Alum-(K) Classification

Help on  Dana Class: Dana Class: (29)Hydrated Acid and Sulfates
  (29.05)where A B (XO4)2 � x(H2O)
  (29.05.05)Alum Group Alum-(K) KAl(SO4)2•12(H2O) P a3 2/m 3 Alum-(Na) NaAl(SO4)2•12(H2O) P a3 2/m 3 Tschermigite (NH4)Al(SO4)2•12(H2O) P a3 2/m 3 Lonecreekite (NH4)(Fe,Al)(SO4)2•12(H2O) P a3 2/m 3 Lanmuchangite! TlAl(SO4)2•12(H2O) P a3 2/m 3
Help on  Strunz Class: Strunz Class: 07.CC.20 07 - SULFATES (SELENATES, TELLURATES)
  07.C - Sulfates (selenates, etc.) without Additional Anions, with H2O
  07.CC -With medium-sized and large cations
07.CC.20 Lonecreekite (NH4)(Fe,Al)(SO4)2•12(H2O) P a3 2/m 3
07.CC.20 Alum-(K) KAl(SO4)2•12(H2O) P a3 2/m 3
07.CC.20 Alum-(Na) NaAl(SO4)2•12(H2O) P a3 2/m 3
07.CC.20 Lanmuchangite! TlAl(SO4)2•12(H2O) P a3 2/m 3
07.CC.20 Tschermigite (NH4)Al(SO4)2•12(H2O) P a3 2/m 3

Other Alum-(K) Information

Help on References: References: NAME( Dana7) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Dana7)
Help on See Also: See Also: Links to other databases for Alum-(K) :
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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Dana No: Strunz No: 07.CC.20





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