Howieite Mineral Data

Howieite Mineral Data +

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General Howieite Information

Chemical Formula:

Na(Fe++,Mn++)10(Fe,Al)2Si12O31(OH)13

Composition:

Molecular Weight = 2,544.93 gm

Sodium 0.90 % Na 1.22 % Na₂O

Magnesium 0.48 % Mg 0.79 % MgO

Manganese 6.48 % Mn 8.36 % MnO

Aluminum 0.64 % Al 1.20 % Al₂O₃

Iron 17.56 % Fe 18.07 % FeO / 5.02 % Fe₂O₃

Silicon 26.49 % Si 56.66 % SiO₂

Hydrogen 0.50 % H 4.50 % H₂O

Oxygen 46.96 % O

______ ______

100.00 % 95.82 % = TOTAL OXIDE

Empirical Formula:

NaFe²⁺_6.4Mn²⁺₃Mg_0.5Fe³⁺_1.6Al_0.62(Si₁₂)2(O₃₁)(OH)_12.7

Environment:

In the Jurassic-aged Franciscan Formation metamorphosed to blue-shist facies (high pressure, low temperature ).

IMA Status:

Approved IMA 1964

Locality:

Laytonville quarry, 5 miles south of Laytonville, Mendocino Co. California. Link to MinDat.org Location Data.

Name Origin:

Named for Robert Andrew Howie (1923-), British mineralogist and petrologist, King's College, London University, UK.

Synonym:

ICSD 6257

PDF 19-571

Howieite Image

Images:

Howieite

Comments: Black vitreous radiating crystalline howieite.
Location: Longvale Quarry, Mendocino County, California, USA. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Howieite Crystallography

Axial Ratios:

a:b:c =1.0405:1:0.981

Cell Dimensions:

a = 10.17, b = 9.774, c = 9.589, Z = 1; alpha = 91.22°, beta = 70.76°, gamma = 108.09° V = 855.25 Den(Calc)= 4.94

Crystal System:

TriclinicSpace Group: P1,P1

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

By Intensity(I/I_o): 9.18(1), 7.91(0.8), 3.25(0.65),

Crystal Structure:

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Wenk H R , American Mineralogist , 59 (1974) p.86-97, Howieite, a new type of chain silicate

Physical Properties of Howieite

Cleavage:

[010] Good, [100] Distinct, [210] Poor

Color:

Dark green, Black.

Density:

3.378

Diaphaniety:

Transparent to Translucent

Habit:

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

Luster:

Greasy (Oily)

Streak:

grayish black

Optical Properties of Howieite

Optical Data:

Biaxial (-), a=1.701, b=1.72, g=1.734, bire=0.0330, 2V(Calc)=80, 2V(Meas)=65.

Pleochroism (x):

golden yellow.

Pleochroism (y):

dark lilac green.

Pleochroism (z):

green.

Calculated Properties of Howieite

Electron Density:

r_electron=4.87 gm/cc
note: r_Howieite=4.94 gm/cc.

Fermion Index

Fermion Index = 0.01679
Boson Index = 0.98321

Photoelectric:

PE_Howieite= 7.90 barns/electron
U=PE_Howieite x r_electron= 38.48 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Howieite is Not Radioactive

Howieite Classification

Dana Class:

69.2.3.1 (69)Inosilicate Chains with Side Branches or Loops

(69.2)with P>2

(69.2.3)Howieite group

69.2.3.1 Howieite Na(Fe,Mn)10(Fe,Al)2Si12O31(OH)13 P1,P1 Tri

69.2.3.2 Taneyamalite (Na,Ca)(Mn,Mg)12[(Si,Al)6O17]2(O,OH)10 P1 1

69.2.3.3 Deerite (Fe,Mn)6(Fe,Al)3Si6O20(OH)5 P 2₁/a 2/m

Strunz Class:

VIII/F.16-20 VIII - Silicates

VIII/F - Inosilicates (chain and band) modified double chains

VIII/F.16 - Deerite - Taneyamalite series

VIII/F.16-10 Deerite (Fe,Mn)6(Fe,Al)3Si6O20(OH)5 P 2₁/a 2/m

VIII/F.16-20 Howieite Na(Fe,Mn)10(Fe,Al)2Si12O31(OH)13 P1,P1 Tri

VIII/F.16-30 Taneyamalite (Na,Ca)(Mn,Mg)12[(Si,Al)6O17]2(O,OH)10 P1 1

VIII/F.16-40 Johninnesite Na2Mg4Mn12(AsO4)2(Si12O35)(OH)6 P1 1

Other Howieite Information

References:

NAME( AntBidBlaNic2) PHYS. PROP.(AntBidBlaNic2) OPTIC PROP.(AntBidBlaNic2)

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

Howieite

Na(Fe++,Mn++)10(Fe,Al)2Si12O31(OH)13
Dana No: 69.2.3.1 Strunz No: VIII/F.16-20
Locality:

Notes: