Mineralogy Database

Stilpnomelane Mineral Data

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General Stilpnomelane Information

Help on Chemical  Formula: Chemical Formula: K(Fe++,Mg,Fe+++)8(Si,Al)12(O,OH)27•n(H2O)
Help on Composition: Composition: Molecular Weight = 1,247.57 gm
   Potassium   3.13 %  K
   Magnesium   2.73 %  Mg
   Aluminum    4.33 %  Al
   Iron       29.54 %  Fe
   Silicon    22.51 %  Si
   Hydrogen    0.57 %  H
   Oxygen     37.19 %  O
             100.00 % 
Help on Empirical Formula: Empirical Formula: KFe2+4.3Mg1.4Fe3+2.3Si10Al2O24(OH)3�2(H2O)
Help on Environment: Environment: Commonly associated with iron ores.
Help on IMA Status: IMA Status: Valid Species (Pre-IMA) 1827
Help on Locality: Locality: Moravia of Czechoslovakia at Sternberg in a bed of limonite. Link to MinDat.org Location Data.
Help on Name Origin: Name Origin: From the Greek for "shining" and "black", in allusion to its luster and color.
Help on Name Pronunciation: Name Pronunciation: Stilpnomelane + Pronunciation Say STILPNOMELANE
Help on Synonym: Synonym: Ferristilpnomelane - high Fe+++
  Ferrostilpnomelane - Low Fe+++

Stilpnomelane Image

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Comments: Golden metallic scaly stilpnomelane on pink orthoclase.
Location: French Creek No. 2 Mine, near Saint Peters, Chester County, Pennsylvania, USA. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Stilpnomelane Crystallography

Help on Axial Ratios: Axial Ratios: a:b:c =1:1:0.8073
Help on Cell Dimensions: Cell Dimensions: a = 21.8, b = 21.8, c = 17.6, Z = 6; alpha = 125.03°, beta = 95.98°, gamma = 120° V = 5,899.18 Den(Calc)= 2.11
Help on Crystal System: Crystal System: Triclinic - Pinacoidal H-M Symbol ( 1) Space Group: P1
Help on X Ray Diffraction: X Ray Diffraction: By Intensity(I/Io): 2.55(1), 4.16(1), 12.3(1),

Physical Properties of Stilpnomelane

Help on Cleavage: Cleavage: {001} Perfect
Help on Color: Color: Brown red, Green, Golden brown, Black.
Help on Density: Density: 2.77 - 2.96, Average = 2.86
Help on Diaphaneity: Diaphaneity: Subtranslucent to opaque
Help on Fracture: Fracture: Brittle - Generally displayed by glasses and most non-metallic minerals.
Help on Habit: Habit: Fibrous - Crystals made up of fibers.
Help on Habit: Habit: Foliated - Two dimensional platy forms.
Help on Habit: Habit: Platy - Sheet forms (e.g. micas).
Help on Hardness: Hardness: 3 - Calcite
Help on Luminescence: Luminescence: Non-fluorescent.
Help on Luster: Luster: Vitreous - Dull
Help on Streak: Streak: gray white

Optical Properties of Stilpnomelane

Help on Optical Data: Optical Data: Biaxial (-), a=1.543-1.634, b=1.576-1.745, g=1.576-1.745, bire=0.0330-0.1110, 2V(Calc)=0, 2V(Meas)=0-40. Dispersion none.
Help on Pleochroism (x): Pleochroism (x): pale yellow, golden yellow, pale brown, or colorless.
Help on Pleochroism (y): Pleochroism (y): deep brown, nearly black, chestnut brown, deep yellowish brown, or light greenish yellow.
Help on Pleochroism (z): Pleochroism (z): deep brown, nearly black, chestnut brown, deep yellowish brown, or light greenish yellow.

Calculated Properties of Stilpnomelane

Help on Electron Density: Electron Density: Bulk Density (Electron Density)=2.46 gm/cc
note: Specific Gravity of Stilpnomelane =2.51 gm/cc.
Help on Fermion Index: Fermion Index: Fermion Index = 0.01
Boson Index = 0.99
Help on Photoelectric: Photoelectric: PEStilpnomelane = 10.10 barns/electron
U=PEStilpnomelane x relectron= 24.89 barns/cc.
Help on Radioactivity: Radioactivity:

GRapi = 44.41 (Gamma Ray American Petroleum Institute Units)
Concentration of Stilpnomelane per GRapi unit = 2.25 (%)

Estimated Radioactivity from Stilpnomelane - barely detectable


Stilpnomelane Classification

Help on  Dana Class: Dana Class: (74)Phyllosilicate Modulated Layers
  (74.01)with joined islands
  (74.01.01)Stilpnomelane group Stilpnomelane K(Fe,Mg,Fe)8(Si,Al)12(O,OH)27•n(H2O) P1 1 Lennilenapeite K6-7(Mg,Mn,Fe,Fe,Zn)48(Si,Al)72(O,OH)216•16(H2O) Unk (pseudo-HEX) Tri Franklinphilite (K,Na)4(Mn,Mg,Zn)48(Si,Al)72(O,OH)216•6(H2O) pseudo-HEX P1 or P1 Tri Bannisterite KCa(Mn,Fe,Zn,Mg)21(Si,Al)32O76(OH)16•4-12(H2O) A2/a 2/m Middendorfite! K3Na2Mn5Si12(O,OH)36•2H2O P 21/m or P 21 Mono
Help on  Strunz Class: Strunz Class: 09.EG.40 09 - SILICATES (Germanates)
  09.E - Phyllosilicates
  09.EG -Double nets with 6-membered and larger rings
09.EG.40 Franklinphilite (K,Na)4(Mn,Mg,Zn)48(Si,Al)72(O,OH)216•6(H2O) pseudo-HEX P1 or P1 Tri
09.EG.40 Ekmanite? (Fe,Mg,Mn,Fe)3(Si,Al)4O10(OH)2•2(H2O) Unk Ortho
09.EG.40 Lennilenapeite K6-7(Mg,Mn,Fe,Fe,Zn)48(Si,Al)72(O,OH)216•16(H2O) Unk (pseudo-HEX) Tri
09.EG.40 Parsettensite (K,Na,Ca)(Mn,Al)7Si8O20(OH)8•2(H2O)(?) C 2/m 2/m
09.EG.40 Stilpnomelane K(Fe,Mg,Fe)8(Si,Al)12(O,OH)27•n(H2O) P1 1

Other Stilpnomelane Information

Help on References: References: NAME( Ford32) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)
Help on See Also: See Also: Links to other databases for Stilpnomelane :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - EUROmin Project
4 - Ecole des Mines de Paris
5 - GeoScienceWorld
6 - Google Images
7 - Google Scholar
8 - Handbook of Mineralogy (MinSocAm)
9 - Handbook of Mineralogy (UofA)
10 - MinDAT
11 - Mineralienatlas (Deutsch)
12 - Minerals in Thin Section-University of North Carolina
13 - Minerals in Thin Sections-Humboldt State
14 - Online Mineral Museum
15 - QUT Mineral Atlas
16 - Ruff.Info

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Dana No: Strunz No: 09.EG.40





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