Chapmanite Mineral Data

Chapmanite Mineral Data

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General Chapmanite Information

Chemical Formula:

Sb+++Fe+++2(SiO4)2(OH)

Composition:

Molecular Weight = 434.62 gm

Iron 25.70 % Fe 33.06 % FeO

Silicon 12.92 % Si 27.65 % SiO₂

Antimony 28.01 % Sb 31.69 % SbO

Hydrogen 0.23 % H 2.07 % H₂O

Oxygen 33.13 % O

______ ______

100.00 % 94.48 % = TOTAL OXIDE

Empirical Formula:

Fe²⁺₂Sb(SiO₄)₂(OH)

Environment:

Intimately associated with silver ores. Antimomy analog to bismutoferrite.

IMA Status:

Valid Species (Pre-IMA) 1924

Locality:

Keeley Mine is South Lorrain near Cobalt, Ontaario, Canada. Link to MinDat.org Location Data.

Name Origin:

Named after the Canadian mineralogist, E. J. Chapman (1821-1904).

Synonym:

ICSD 87100

PDF 11-135

Chapmanite Image

Images:

Chapmanite

Comments: Green, earthy chapmanite on quartz-sulfide matrix.
Location: Neue Hoffnung Gottes Mine, Br?unsdorf, Freiberg District, Erzgebirge, Saxony, Germany. Scale: Picture size 5 mm.
© Thomas Witzke / Abraxas-Verlag

Chapmanite Crystallography

Axial Ratios:

a:b:c =0.5773:1:0.8565

Cell Dimensions:

a = 5.19, b = 8.99, c = 7.7, Z = 2; beta = 100.67° V = 353.06 Den(Calc)= 4.09

Crystal System:

Monoclinic - DomaticH-M Symbol (m) Space Group: Cm

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

By Intensity(I/I_o): 3.58(1), 7.63(0.9), 3.19(0.9),3.88(0.8), 2.59(0.7), 2.9(0.7), 2.54(0.3), 4.17(0.3),

Crystal Structure:

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Ballirano P , Maras A , Marchetti F , Merlino S , Perchiazzi N , Powder Diffraction , 13 (1998) p.44-49, Rietveld refinement of chapmanite SbFe2Si2O8OH,, a TO dioctahderal kaolinite-like mineral, Locality: Tafone mine, Tucsany, Italy

Physical Properties of Chapmanite

Color:

Yellowish green, Yellow, Olive green.

Density:

3.58 - 3.7, Average = 3.64

Diaphaniety:

Translucent

Fracture:

Uneven - Flat surfaces (not cleavage) fractured in an uneven pattern.

Habit:

Earthy - Dull, clay-like texture with no visible crystalline affinities, (e.g. howlite).

Habit:

Granular - Generally occurs as anhedral to subhedral crystals in matrix.

Hardness:

2.5 - Finger Nail

Luminescence:

None.

Luster:

Adamantine

Streak:

yellowish green

Optical Properties of Chapmanite

Gladstone-Dale:

CI meas= -0.995 (Poor) - where the CI = (1-KPDmeas/KC)
CI calc= -0.775 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2249,KPDmeas= 0.2527,KC= 0.1267

Optical Data:

Biaxial (-), a=1.85, b=1.95, g=1.96, bire=0.1100, 2V(Calc)=32, 2V(Meas)=small. Dispersion none.

Pleochroism (x):

none.

Pleochroism (y):

none.

Pleochroism (z):

none.

Calculated Properties of Chapmanite

Electron Density:

r_electron=3.84 gm/cc
note: r_Chapmanite=4.09 gm/cc.

Fermion Index

Fermion Index = 0.01164
Boson Index = 0.98836

Photoelectric:

PE_Chapmanite= 96.25 barns/electron
U=PE_Chapmanite x r_electron= 369.57 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Chapmanite is Not Radioactive

Chapmanite Classification

Dana Class:

71.1.3.2 (71)Phyllosilicate Sheets of Six-Membered Rings

(71.1)with 1:1 layers

(71.1.3)Bismutoferrite group

71.1.3.1 Bismutoferrite BiFe2(SiO4)2(OH) Cm m

71.1.3.2 Chapmanite SbFe2(SiO4)2(OH) Cm m

Strunz Class:

VIII/B.06-10 VIII - Silicates

VIII/B - Nesosubsilicates, with anions unfamiliar to tetraheders, cations of octahedral and tetrahedral orientation [4/6]

VIII/B.06 - Chapmanite - Bismutoferrite series

VIII/B.06-10 Chapmanite SbFe2(SiO4)2(OH) Cm m

VIII/B.06-20 Bismutoferrite BiFe2(SiO4)2(OH) Cm m

Other Chapmanite Information

References:

NAME( Duda&Rejl90) PHYS. PROP.(Dana8) OPTIC PROP.(Ford32)

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Chapmanite

Sb+++Fe+++2(SiO4)2(OH)
Dana No: 71.1.3.2 Strunz No: VIII/B.06-10
Locality:

Notes: