Stilpnomelane Mineral Data

Stilpnomelane Mineral Data +

[Newest Minerals] [Rare Minerals] [Past Sale Items] [About Us] [A-Rocks Auctions]
T G Fine Minerals sells Australian Minerals from all the classic and current localities
We are one the most comprehensive sellers of these (Aussie) minerals in the world
Broken Hill specimens are our specialty along with fine worldwide minerals, Australian opals, fossils & gems

General Stilpnomelane Information

Chemical Formula:

K(Fe++,Mg,Fe+++)8(Si,Al)12(O,OH)27·n(H2O)

Composition:

Molecular Weight = 1,235.84 gm

Potassium 2.21 % K

Magnesium 2.75 % Mg

Aluminum 4.37 % Al

Iron 29.83 % Fe

Silicon 22.73 % Si

Hydrogen 0.57 % H

Oxygen 37.54 % O

______

100.00 %

Empirical Formula:

K_0.7Fe²⁺_3.3Mg_1.4Fe³⁺_3.3Si₁₀Al₂O₂₄(OH)₃·2(H₂O)

Environment:

Commonly associated with iron ores.

IMA Status:

Valid Species (Pre-IMA) 1827

Locality:

Moravia of Czechoslovakia at Sternberg in a bed of limonite. Link to MinDat.org Location Data.

Name Origin:

From the Greek for "shining" and "black", in allusion to its luster and color.

Synonym:

Ferristilpnomelane-high Fe+++

Ferrostilpnomelane-low Fe+++

Stilpnomelane Image

Images:

Stilpnomelane

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

Axial Ratios:

a:b:c =1:1:0.8033

Cell Dimensions:

a = 22.2, b = 22.2, c = 17.835, Z = 9; alpha = 125.03°, beta = 95.98°, gamma = 120° V = 6,199.34 Den(Calc)= 2.98

Crystal System:

Triclinic - PinacoidalH-M Symbol ( 1) Space Group: P1

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

By Intensity(I/I_o): 2.55(1), 4.16(1), 12.3(1),

Physical Properties of Stilpnomelane

Cleavage:

[001] Perfect

Color:

Brown red, Green, Golden brown, Black.

Density:

2.77 - 2.96, Average = 2.86

Diaphaniety:

Subtranslucent to opaque

Fracture:

Brittle - Generally displayed by glasses and most non-metallic minerals.

Habit:

Fibrous - Crystals made up of fibers.

Habit:

Foliated - Two dimensional platy forms.

Habit:

Platy - Sheet forms (e.g. micas).

Hardness:

3 - Calcite

Luminescence:

Non-fluorescent.

Luster:

Vitreous - Dull

Streak:

gray white

Optical Properties of Stilpnomelane

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.

Pleochroism (x):

pale yellow, golden yellow, pale brown, or colorless.

Pleochroism (y):

deep brown, nearly black, chestnut brown, deep yellowish brown, or light greenish yellow.

Pleochroism (z):

deep brown, nearly black, chestnut brown, deep yellowish brown, or light greenish yellow.

Calculated Properties of Stilpnomelane

Electron Density:

r_electron=2.93 gm/cc
note: r_{Stilpnomelane}=2.98 gm/cc.

Fermion Index

Fermion Index = 0.01987
Boson Index = 0.98013

Photoelectric:

PE_{Stilpnomelane}= 10.10 barns/electron
U=PE_{Stilpnomelane} x r_electron= 29.56 barns/cc.

Radioactivity:

GRapi = 31.37 (Gamma Ray American Petroleum Institute Units)

Estimated Radioactivity from Stilpnomelane - barely detectable

Stilpnomelane Classification

Dana Class:

74.1.1.1 (74)Phyllosilicate Modulated Layers

(74.1)with joined islands

(74.1.1)Stilpnomelane group

74.1.1.1 Stilpnomelane K(Fe,Mg,Fe)8(Si,Al)12(O,OH)27·n(H2O) P1 1

74.1.1.2 Lennilenapeite K6-7(Mg,Mn,Fe,Fe,Zn)48(Si,Al)72(O,OH)216·16(H2O) Unk (pseudo-HEX) Tri

74.1.1.3 Franklinphilite (K,Na)4(Mn,Mg,Zn)48(Si,Al)72(O,OH)216·6(H2O) pseudo-HEX P1 or P1 Tri

74.1.1.4 Bannisterite KCa(Mn,Fe,Zn,Mg)21(Si,Al)32O76(OH)16·4-12(H2O) A2/a 2/m

Strunz Class:

VIII/H.17-40 VIII - Silicates

VIII/H - Phyllosilicates (layered) Mica like layered silicates with [Si4O10]4- and related groups

VIII/H.17 - Stilpnomelane series

VIII/H.17-10 Bannisterite KCa(Mn,Fe,Zn,Mg)21(Si,Al)32O76(OH)16·4-12(H2O) A2/a 2/m

VIII/H.17-20 Bariumbannisterite* (K,H3O)(Ba,Ca)(Mn,Fe,Mg)21(Si,Al)32O80(O,OH)16·4-12(H2O) Mono

VIII/H.17-30 Lennilenapeite K6-7(Mg,Mn,Fe,Fe,Zn)48(Si,Al)72(O,OH)216·16(H2O) Unk (pseudo-HEX) Tri

VIII/H.17-40 Stilpnomelane K(Fe,Mg,Fe)8(Si,Al)12(O,OH)27·n(H2O) P1 1

VIII/H.17-45 Franklinphilite (K,Na)4(Mn,Mg,Zn)48(Si,Al)72(O,OH)216·6(H2O) pseudo-HEX P1 or P1 Tri

VIII/H.17-50 Parsettensite (K,Na,Ca)(Mn,Al)7Si8O20(OH)8·2(H2O)(?) C 2/m 2/m

VIII/H.17-60 Ganophyllite (K,Na)2(Mn,Al,Mg)8(Si,Al)12O29(OH)7·8-9(H2O) A2/a 2/m

VIII/H.17-70 Eggletonite Na2Mn8[Si11AlO29](OH)7·11(H2O) Ia or I2/a Mono

VIII/H.17-75 Tamaite! (Ca,K,Ba,Na)3-4Mn24(Si,Al)40(O,OH)112·21(H2O) P 2₁/a 2/m

VIII/H.17-80 Ekmanite? (Fe,Mg,Mn,Fe)3(Si,Al)4O10(OH)2·2(H2O) Unk Ortho

Other Stilpnomelane Information

References:

NAME( Ford32) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)

Search for Stilpnomelane using:

[ALTAVISTA] [AOL] [About.com] [All-The-Web] [HotBot] [Ixquick] [LookSmart] [MAMMA] [MSN.COM] [Netscape] [Teoma] [Wikipedia] [YAHOO]

Visit our Advertisers for Stilpnomelane :
AA Mineral Specimens
B and L Minerals
Dan Weinrich Fine Minerals
Dan Weinrich Auctions
e-Rocks Auctions
Excalibur Minerals
Exceptional Minerals
Fabre Minerals
Greenside Minerals
John Betts Fine Minerals
Masons Minerals
Minernet.it
Mineral News
Mineral of the Month Club
MineralsWeb Fine Minerals
Rockshop.cz Kalat Fine Minerals
T G Fine Minerals
Wrights Rock Shop

Translate Stilpnomelane Mineral Data :

Ask about Stilpnomelane here :
Ask-A-Mineralogist from the Mineralogical Society of America
Mindat.org's Discussion Groups
Original Rockhounds Discussion Group
Rockhounds Discussion Group on Yahoo Groups
Mineral Discussion Forum from Fabre Minerals - also available in Español

Print or Cut-and-Paste your Stilpnomelane Specimen Label here :

Stilpnomelane

K(Fe++,Mg,Fe+++)8(Si,Al)12(O,OH)27·n(H2O)
Dana No: 74.1.1.1 Strunz No: VIII/H.17-40
Locality:

Notes: