Bannisterite Mineral Data

Bannisterite Mineral Data +

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General Bannisterite Information

Chemical Formula:

KCa(Mn,Fe++,Zn,Mg)21(Si,Al)32O76(OH)16·4-12(H2O)

Composition:

Molecular Weight = 3,734.70 gm

Potassium 0.84 % K 1.01 % K₂O

Sodium 0.12 % Na 0.17 % Na₂O

Calcium 0.97 % Ca 1.35 % CaO

Magnesium 1.89 % Mg 3.13 % MgO

Manganese 17.95 % Mn 23.17 % MnO

Aluminum 2.17 % Al 4.10 % Al₂O₃

Zinc 3.68 % Zn 4.58 % ZnO

Iron 5.23 % Fe 5.58 % FeO / 1.28 % Fe₂O₃

Silicon 21.43 % Si 45.85 % SiO₂

Hydrogen 1.09 % H 9.74 % H₂O

Oxygen 44.64 % O

______ ______

100.00 % 99.96 % = TOTAL OXIDE

Empirical Formula:

K_0.8Na_0.2Ca_0.9Mn²⁺_12.2Fe²⁺_2.9Mg_2.9Zn_2.1Fe³⁺_0.6Si_28.5Al₃O₇₆(OH)₁₆·12.2(H₂O)

Environment:

Metamorphosed Mn-Zn orebodies.

IMA Status:

Valid Species (Pre-IMA) 1936

Locality:

In the Banallt mine, Rhiw, Lleyn Peninsula, Wales. Link to MinDat.org Location Data.

Name Origin:

Named for Dr. Frederick Allen Bannister (1901-?), formerly Keeper of Minerals, British Museum (Natural History), London, England.

Synonym:

ICSD 80078

PDF 46-1281

Bannisterite Image

Images:

Bannisterite

Comments: Deep red micaceous bannisterite.
Location: Zinc Mine, Broken Hill, New South Wales, Australia. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Bannisterite Crystallography

Axial Ratios:

a:b:c =1.3602:1:1.507

Cell Dimensions:

a = 22.265, b = 16.368, c = 24.668, Z = 4; beta = 94.285° V = 8,964.72 Den(Calc)= 2.77

Crystal System:

Monoclinic - PrismaticH-M Symbol (2/m) Space Group: A2/a

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

By Intensity(I/I_o): 12.33(1), 3.44(0.2), 4.1(0.16),

Crystal Structure:

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Heaney P J , Post J E , Evans H T , Clays and Clay Minerals , 40 (1992) p.129-144, The crystal structure of bannisterite, Locality: Broken Hill, Australia

View Additional jPOWD Structure files for Bannisterite
[1]

Physical Properties of Bannisterite

Cleavage:

[001] Perfect, [???] Distinct

Color:

Dark brown, Black.

Density:

2.83 - 2.84, Average = 2.83

Diaphaniety:

Translucent

Habit:

Aggregates - Made of numerous individual crystals or clusters.

Habit:

Bladed - Aggregates of thin lath-like crystals (e.g. kyanite).

Habit:

Prismatic - Crystals Shaped like Slender Prisms (e.g. tourmaline).

Hardness:

4 - Fluorite

Luster:

Resinous

Optical Properties of Bannisterite

Gladstone-Dale:

CI meas= -0.007 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= -0.031 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2116,KPDmeas= 0.2067,KC= 0.2053

Optical Data:

Biaxial (?), a=1.544-1.574, b=1.586-1.611, g=1.589-1.612, bire=0.0380-0.0450, 2V(Calc)=18-28, 2V(Meas)=small. Dispersion r < v moderate.

Calculated Properties of Bannisterite

Electron Density:

r_electron=2.80 gm/cc
note: r_Bannisterite=2.84 gm/cc.

Fermion Index

Fermion Index = 0.01474
Boson Index = 0.98526

Photoelectric:

PE_Bannisterite= 8.99 barns/electron
U=PE_Bannisterite x r_electron= 25.14 barns/cc.

Radioactivity:

GRapi = 11.93 (Gamma Ray American Petroleum Institute Units)

Estimated Radioactivity from Bannisterite - barely detectable

Bannisterite Classification

Dana Class:

74.1.1.4 (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.17-10 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 Bannisterite Information

References:

NAME( AntBidBlaNic2) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(AntBidBlaNic2)

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Bannisterite

KCa(Mn,Fe++,Zn,Mg)21(Si,Al)32O76(OH)16·4-12(H2O)
Dana No: 74.1.1.4 Strunz No: VIII/H.17-10
Locality:

Notes: