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Polyhalite Mineral Data

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General Polyhalite Information

Help on Chemical  Formula: Chemical Formula: K2Ca2Mg(SO4)4•2(H2O)
Help on Composition: Composition: Molecular Weight = 602.94 gm
   Potassium  12.97 %  K    15.62 % K2O
   Calcium    13.29 %  Ca   18.60 % CaO
   Magnesium   4.03 %  Mg    6.68 % MgO
   Hydrogen    0.67 %  H     5.98 % H2O
   Sulfur     21.27 %  S    53.12 % SO3
   Oxygen     47.76 %  O
             ______        ______ 
             100.00 %      100.00 % = TOTAL OXIDE
Help on Empirical Formula: Empirical Formula: K2Ca2Mg(SO4)4•2(H2O)
Help on Environment: Environment: Sedimentary marine evaporite deposits.
Help on IMA Status: IMA Status: Valid Species (Pre-IMA) 1818
Help on Locality: Locality: Potash beds near Carlsbad, New Mexico. Link to MinDat.org Location Data.
Help on Name Origin: Name Origin: From the Greek, polys, meaning "much" and hals, meaning "salt." in allusion to the many salt components in the formulae..
Help on Name Pronunciation: Name Pronunciation: Polyhalite + Pronunciation Say POLYHALITE
Help on Synonym: Synonym: ICSD 6303
  PDF 21-982

Polyhalite Image

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Comments: White crystals of polyhalite in matrix.
Location: Ronneburg U deposit, Gera district, Thuringia, Germany. Scale: Picture size 1.5 mm.
© Thomas Witzke / Abraxas-Verlag

Polyhalite Crystallography

Help on Axial Ratios: Axial Ratios: a:b:c =0.7158:1:0.4654
Help on Cell Dimensions: Cell Dimensions: a = 11.69, b = 16.33, c = 7.6, Z = 4; alpha = 91.6°, beta = 90°, gamma = 91.9° V = 1,449.46 Den(Calc)= 2.76
Help on Crystal System: Crystal System: Triclinic Space Group: P 1,P1
Help on X Ray Diffraction: X Ray Diffraction: By Intensity(I/Io): 2.9(1), 3.18(0.7), 2.85(0.16),
Help on Forms: Forms:

Dbl Clk - Start-Stop Rotation
RMB - Cycle Display Modes
Drag1 - Manipulate Crystal
Drag2 - Resize

S - Stereo
I - Indicies
<space> - Start-Stop Rotation
F - Fit to Screen
M - Menu

Help on Above

Forms: ( 0 1 0) ( 1 3 1) ( 1 1 0) ( 1 0 0) ( 0 0 1)

Warning: this java applet does not work in some browsers because of security restrictions.


Physical Properties of Polyhalite

Help on Cleavage: Cleavage: {101} Perfect
Help on Color: Color: Colorless, Gray, Gray white, White, Pink.
Help on Density: Density: 2.77 - 2.78, Average = 2.77
Help on Diaphaneity: Diaphaneity: Transparent to Translucent
Help on Fracture: Fracture: Brittle - Conchoidal - Very brittle fracture producing small, conchoidal fragments.
Help on Habit: Habit: Massive - Fibrous - Distinctly fibrous fine-grained forms.
Help on Habit: Habit: Massive - Lamellar - Distinctly foliated fine-grained forms.
Help on Hardness: Hardness: 2.5-3.5 - Finger Nail-Copper Penny
Help on Luster: Luster: Vitreous (Glassy)
Help on Streak: Streak: white

Optical Properties of Polyhalite

Help on Gladstone-Dale: Gladstone-Dale: CI meas= -0.019 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= -0.024 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2022,KPDmeas= 0.2011,KC= 0.1974
Ncalc = 1.54 - 1.55
Help on Optical Data: Optical Data: Biaxial (-), a=1.546-1.548, b=1.558-1.562, g=1.567, bire=0.0190-0.0210, 2V(Calc)=60-80, 2V(Meas)=60-62.
Help on Pleochroism (x): Pleochroism (x): colorless.
Help on Pleochroism (y): Pleochroism (y): colorless.
Help on Pleochroism (z): Pleochroism (z): colorless.

Calculated Properties of Polyhalite

Help on Electron Density: Electron Density: Bulk Density (Electron Density)=2.78 gm/cc
note: Specific Gravity of Polyhalite =2.78 gm/cc.
Help on Fermion Index: Fermion Index: Fermion Index = 0.0060518431
Boson Index = 0.9939481569
Help on Photoelectric: Photoelectric: PEPolyhalite = 4.30 barns/electron
U=PEPolyhalite x relectron= 11.94 barns/cc.
Help on Radioactivity: Radioactivity:

GRapi = 187.47 (Gamma Ray American Petroleum Institute Units)
Concentration of Polyhalite per GRapi unit = 0.53 (%)

Estimated Radioactivity from Polyhalite - barely detectable


Polyhalite Classification

Help on  Dana Class: Dana Class: (29)Hydrated Acid and Sulfates
  (29.04)where (A+)2 Bn (XO4)p � x(H2O)
  (29.04.05)Dana Group Polyhalite K2Ca2Mg(SO4)4•2(H2O) P 1,P1 Tri Leightonite K2Ca2Cu(SO4)4•2(H2O) C 2/c 2/m
Help on  Strunz Class: Strunz Class: 07.CC.65 07 - SULFATES (SELENATES, TELLURATES)
  07.C - Sulfates (selenates, etc.) without Additional Anions, with H2O
  07.CC -With medium-sized and large cations
07.CC.65 Polyhalite K2Ca2Mg(SO4)4•2(H2O) P 1,P1 Tri

Other Polyhalite Information

Help on References: References: NAME( Duda&Rejl90) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Ford32)
Help on See Also: See Also: Links to other databases for Polyhalite :
1 - Am. Min. Crystal Structure Database
2 - Amethyst Galleries' Mineral Gallery
3 - Athena
4 - EUROmin Project
5 - Ecole des Mines de Paris
6 - GeoScienceWorld
7 - Google Images
8 - Google Scholar
9 - Handbook of Mineralogy (MinSocAm)
10 - Handbook of Mineralogy (UofA)
11 - MinDAT
12 - Mineralienatlas (Deutsch)
13 - Online Mineral Museum
14 - QUT Mineral Atlas
15 - Ruff.Info

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Dana No: Strunz No: 07.CC.65





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