Magnesio-axinite Mineral Data

Magnesio-axinite Mineral Data

General Magnesio-axinite Information

Chemical Formula:

Ca2MgAl2BO3Si4O12(OH)

Composition:

Molecular Weight = 538.57 gm

Calcium 14.88 % Ca 20.82 % CaO

Magnesium 4.51 % Mg 7.48 % MgO

Aluminum 10.02 % Al 18.93 % Al₂O₃

Silicon 20.86 % Si 44.62 % SiO₂

Boron 2.01 % B 6.46 % B₂O₃

Hydrogen 0.19 % H 1.67 % H₂O

Oxygen 47.53 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Ca₂MgAl₂(BO₃)Si₄O₁₂(OH)

Environment:

Contact metamorphic, hydrothermal, and alpine vein rocks.

IMA Status:

Approved IMA 1975

Locality:

Tanzania. Link to MinDat.org Location Data.

Name Origin:

From the Greek acine - "axe" in allusion to the acute shape of typical crystals and the Greek, "Magnesia" a district in Thessaly in reference to the Mg in the chemical formula.

Synonym:

Axinite

Magnesio-axinite Image

Images:

Magnesio-axinite

Comments: Cinnamon brown crystal of "axinite" (probably magnesio-axinite).
Location: El Fenomino Tungsten Mine, Northern Baja Californa, Mexico. Scale: Crystal size 2 cm.
© Dave Barthelmy

Magnesio-axinite Crystallography

Axial Ratios:

a:b:c =0.9757:1:0.7778

Cell Dimensions:

a = 8.933, b = 9.155, c = 7.121, Z = 2; alpha = 102.59°, beta = 98.28°, gamma = 88.09° V = 562.13 Den(Calc)= 3.18

Crystal System:

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

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

By Intensity(I/I_o): 2.796(1), 3.139(0.65), 3.44(0.65),

Forms:

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Forms: [ 1 1 1] [ 1 1 1] [ 1 0 0] [ 1 1 0] [ 2 0 1] [ 1 1 0]

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Crystal Structure:

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Andreozzi G B , Lucchesi S , Graziani G , European Journal of Mineralogy , 12 (2000) p.1185-1194, Structural study of magnesioaxinite and its crystal-chemical relations, with axinite-group minerals

Physical Properties of Magnesio-axinite

Cleavage:

[100] Distinct, [001] Poor, [110] Poor

Color:

Brown, Purplish blue, Gray, Greenish yellow.

Density:

3.27 - 3.29, Average = 3.28

Diaphaniety:

Translucent to transparent

Fracture:

Brittle - Conchoidal - Very brittle fracture producing small, conchoidal fragments.

Habit:

Lamellar - Thin laminae producing a lamellar structure.

Habit:

Massive - Granular - Common texture observed in granite and other igneous rock.

Hardness:

6.5-7 - Pyrite-Quartz

Luminescence:

Fluorescent.

Luster:

Vitreous (Glassy)

Streak:

white

Optical Properties of Magnesio-axinite

Gladstone-Dale:

CI meas= 0.003 (Superior) - where the CI = (1-KPDmeas/KC)
CI calc= -0.029 (Excellent) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2164,KPDmeas= 0.2098,KC= 0.2103

Optical Data:

Biaxial (-), a=1.672-1.693, b=1.677-1.701, g=1.681-1.704, bire=0.0090-0.0110, 2V(Calc)=62-82, 2V(Meas)=69-87. Dispersion strong, r < v.

Pleochroism (x):

colorless, yellow, light brown, yellow brown, or pale green.

Pleochroism (y):

colorless, deep yellow, deep blue, pale violet, or violet.

Pleochroism (z):

colorless, pale green, olive yellow, brown, or dark violet.

Calculated Properties of Magnesio-axinite

Electron Density:

r_electron=3.26 gm/cc
note: r_{Magnesio-axinite}=3.28 gm/cc.

Fermion Index

Fermion Index = 0.01867
Boson Index = 0.98133

Photoelectric:

PE_{Magnesio-axinite}= 3.05 barns/electron
U=PE_{Magnesio-axinite} x r_electron= 9.95 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Magnesio-axinite is Not Radioactive

Magnesio-axinite Classification

Dana Class:

56.2.2.2 (56)Sorosilicate Si2O7 Groups and O, OH, F. and H2O

(56.2)with cations in [4] and/or >[4] coordination

(56.2.2)Axinite group

56.2.2.1 Ferroaxinite Ca2FeAl2BO3Si4O12(OH) P1 1

56.2.2.2 Magnesio-axinite Ca2MgAl2BO3Si4O12(OH) P1 1

56.2.2.3 Manganaxinite Ca2MnAl2BO3Si4O12(OH) P1 1

56.2.2.4 Tinzenite (Ca,Mn,Fe)3Al2BO3Si4O12(OH) P1 1

Strunz Class:

VIII/E.06-10 VIII - Silicates

VIII/E - Cyklosilicates, quadruplet rings [Si4O11]8-

VIII/E.06 - Axinite group, Magnesio-axinite - Ashburtonite series

VIII/E.06-10 Magnesio-axinite Ca2MgAl2BO3Si4O12(OH) P1 1

VIII/E.06-20 Ferroaxinite Ca2FeAl2BO3Si4O12(OH) P1 1

VIII/E.06-30 Manganaxinite Ca2MnAl2BO3Si4O12(OH) P1 1

VIII/E.06-40 Tinzenite (Ca,Mn,Fe)3Al2BO3Si4O12(OH) P1 1

VIII/E.06-50 Papagoite CaCuAlSi2O6(OH)3 C 2/m 2/m

VIII/E.06-60 Ashburtonite HPb4Cu4Si4O12(HCO3)4(OH)4Cl I 4/m 4/m

Other Magnesio-axinite Information

References:

NAME( Duda&Rejl90) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Heinrich65)

See Also:

Links to other databases for Magnesio-axinite :
1 -Am. Min. Crystal Structure Database 2 -Athena 3 - Crocoite.com Mineral Locations 4 - EUROmin Project 5 -Google Images 6 -Google Scholar 7 -MinDAT 8 -MinMax(Deutsch) 9 -MinMax(English) 10 -Mineralienatlas (Deutsch) 11 -QUT Mineral Atlas

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Magnesio-axinite

Ca2MgAl2BO3Si4O12(OH)
Dana No: 56.2.2.2 Strunz No: VIII/E.06-10
Locality:

Notes: