Ottrelite Mineral Data

Ottrelite Mineral Data +

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General Ottrelite Information

Chemical Formula:

(Mn,Fe++,Mg)2Al4Si2O10(OH)4

Composition:

Molecular Weight = 490.11 gm

Magnesium 2.48 % Mg 4.11 % MgO

Manganese 10.09 % Mn 13.03 % MnO

Aluminum 21.47 % Al 40.57 % Al₂O₃

Iron 7.98 % Fe 8.80 % FeO / 1.63 % Fe₂O₃

Silicon 11.46 % Si 24.52 % SiO₂

Hydrogen 0.82 % H 7.35 % H₂O

Oxygen 45.70 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Mn²⁺_0.9Fe²⁺_0.6Mg_0.5Al_3.9Fe³⁺_0.1Si₂O₁₀(OH)₄

Environment:

Formed under non-shearing stress conditions in veins and cavities within low- to medium-grade metamorphic rocks.

IMA Status:

Valid Species (Pre-IMA) 1819

Locality:

In Belgium, in the Ardennes Mountains, from Ottre, Salmchateau, and Veilsalm. Link to MinDat.org Location Data.

Name Origin:

Named for the locality.

Ottrelite Image

Images:

Ottrelite

Comments: Dark green crystalline ottrelite in quartz.
Location: Vielsalm, Luxembourg, Belgium. Scale: See Photo.
© Jeff Weissman / Photographic Guide to Mineral Species

Ottrelite Crystallography

Axial Ratios:

a:b:c =1.7332:1:3.3212

Cell Dimensions:

a = 9.505, b = 5.484, c = 18.214, Z = 4; beta = 101.767° V = 929.46 Den(Calc)= 3.50

Crystal System:

Monoclinic - PrismaticH-M Symbol (2/m) Space Group: C 2/c

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

By Intensity(I/I_o): 4.46(1), 2.973(0.8), 2.686(0.45),1.585(0.4), 2.439(0.4), 2.461(0.25), 2.375(0.2),

Physical Properties of Ottrelite

Cleavage:

[001] Perfect, [110] Indistinct

Color:

Pistachio green.

Density:

3.52

Diaphaniety:

Translucent

Habit:

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

Habit:

Scaly - Morphology like fish scales.

Hardness:

6-7 - Orthoclase-Quartz

Luster:

Vitreous (Glassy)

Streak:

greenish gray

Optical Properties of Ottrelite

Optical Data:

Biaxial (+), a=1.709-1.725, b=1.712-1.726, g=1.716-1.732, bire=0.0070, 2V(Calc)=46-82, 2V(Meas)=46-70. Dispersion r > v strong.

Pleochroism (x):

olive yellow.

Pleochroism (y):

pale greenish yellow.

Pleochroism (z):

very light yellow.

Calculated Properties of Ottrelite

Electron Density:

r_electron=3.45 gm/cc
note: r_Ottrelite=3.50 gm/cc.

Fermion Index

Fermion Index = 0.00974
Boson Index = 0.99026

Photoelectric:

PE_Ottrelite= 6.03 barns/electron
U=PE_Ottrelite x r_electron= 20.79 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Ottrelite is Not Radioactive

Ottrelite Classification

Dana Class:

52.3.3.3 (52)Nesosilicate Insular SiO4 Groups and O, OH, F, and H2O

(52.3)with cations in [6] coordination only

(52.3.3)Chloritoid group

52.3.3.1 Chloritoid (Fe,Mg,Mn)2Al4Si2O10(OH)4 P1 1

52.3.3.2 Magnesiochloritoid MgAl2SiO5(OH)2 C 2/c 2/m

52.3.3.3 Ottrelite (Mn,Fe,Mg)2Al4Si2O10(OH)4 C 2/c 2/m

52.3.3.4 Carboirite-VIII Fe(Al,Ge)2O[(Ge,Si)O4](OH)2 C1 1

Strunz Class:

VIII/B.24-30 VIII - Silicates

VIII/B - Nesosubsilicates, with anions unfamiliar to tetraheders, cationes with coordinationnumber between [8] and [12]

VIII/B.24 - Magnesiochloritoid - Ottrelite series

VIII/B.24-10 Magnesiochloritoid MgAl2SiO5(OH)2 C 2/c 2/m

VIII/B.24-20 Chloritoid (Fe,Mg,Mn)2Al4Si2O10(OH)4 P1 1

VIII/B.24-30 Ottrelite (Mn,Fe,Mg)2Al4Si2O10(OH)4 C 2/c 2/m

Other Ottrelite Information

References:

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

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Ottrelite

(Mn,Fe++,Mg)2Al4Si2O10(OH)4
Dana No: 52.3.3.3 Strunz No: VIII/B.24-30
Locality:

Notes: