Staurolite Mineral Data

Staurolite Mineral Data +

General Staurolite Information

Chemical Formula:

(Fe++,Mg)2Al9(Si,Al)4O20(O,OH)4

Composition:

Molecular Weight = 811.89 gm

Lithium 0.09 % Li 0.18 % Li₂O

Magnesium 0.30 % Mg 0.50 % MgO

Aluminum 28.91 % Al 54.63 % Al₂O₃

Iron 9.63 % Fe 12.39 % FeO

Silicon 13.49 % Si 28.86 % SiO₂

Hydrogen 0.29 % H 2.55 % H₂O

Oxygen 47.30 % O

______ ______

100.00 % 99.11 % = TOTAL OXIDE

Empirical Formula:

Fe²⁺_1.4Li_0.1Mg_0.1Al_8.6Si_3.9Al_0.1O_21.7(OH)_2.3

Environment:

Metamorphosed aluminous sedimentary rocks.

IMA Status:

Valid Species (Pre-IMA) 1792

Locality:

Common world wide occurrences. Link to MinDat.org Location Data.

Name Origin:

From the Greek, stauros - "cross" and lithos - "stone" in allusion to the common cross shaped twins of the crystals.

Synonym:

ICSD 67446

PDF 41-1484

Staurotide

Staurolite Image

Images:

Staurolite

Comments: Cruciform twinned staurolite crystals without matrix.
Location: Marble, Cherokee Co., North Carolina, USA. Scale: 3x2.5x1.5 cm.
© John Betts - Fine Minerals

Staurolite Crystallography

Axial Ratios:

a:b:c =0.4741:1:0.3405

Cell Dimensions:

a = 7.88, b = 16.62, c = 5.66, Z = 2; beta = 90° V = 741.27 Den(Calc)= 3.64

Crystal System:

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

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

By Intensity(I/I_o): 2.693(1), 3.012(1), 2.372(0.8),

Forms:

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

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Crystal Structure:

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Smith J V , American Mineralogist , 53 (1968) p.1139-1155, The crystal structure of staurolite

View Additional jPOWD Structure files for Staurolite
[1] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [2] [20] [21] [22] [23] [24] [3] [4] [5] [6] [7] [8] [9]

Physical Properties of Staurolite

Cleavage:

[010] Distinct

Color:

Brownish yellow, Brownish black, Yellow brown, Dark brown, Reddish brown.

Density:

3.65 - 3.77, Average = 3.71

Diaphaniety:

Translucent to opaque

Fracture:

Sub Conchoidal - Fractures developed in brittle materials characterized by semi-curving surfaces.

Habit:

Tabular - Form dimensions are thin in one direction.

Habit:

Twinning Common - Crystals are usually twinned.

Hardness:

7-7.5 - Quartz-Garnet

Luminescence:

Non-fluorescent.

Luster:

Vitreous - Dull

Streak:

gray

Optical Properties of Staurolite

Gladstone-Dale:

CI meas= 0.025 (Excellent) - where the CI = (1-KPDmeas/KC)
CI calc= 0.006 (Superior) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2053,KPDmeas= 0.2014,KC= 0.2066

Optical Data:

Biaxial (+), a=1.736-1.747, b=1.74-1.754, g=1.745-1.762, bire=0.0090-0.0150, 2V(Calc)=84-88, 2V(Meas)=88. Dispersion weak to moderate, r > v.

Pleochroism (x):

colorless, pale yellow, or yellowish red.

Pleochroism (y):

colorless, pale yellow, or yellowish red.

Pleochroism (z):

light yellow, orange yellow, or hyacinth red.

Calculated Properties of Staurolite

Electron Density:

r_electron=3.59 gm/cc
note: r_Staurolite=3.64 gm/cc.

Fermion Index

Fermion Index = 0.00893
Boson Index = 0.99107

Photoelectric:

PE_Staurolite= 4.22 barns/electron
U=PE_Staurolite x r_electron= 15.15 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)

Staurolite is Not Radioactive

Staurolite Classification

Dana Class:

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

(52.2)with cations in [4] and >[4] coordination

(52.2.3)Dana Group

52.2.3.1 Staurolite (Fe,Mg)2Al9(Si,Al)4O20(O,OH)4 C 2/m 2/m

52.2.3.2 Magnesiostaurolite! []4Mg4Al16(Al,[])2Si8O40[O6,(OH)2] C 2/m 2/m

52.2.3.3 Zincostaurolite! []4Zn4Al16(Al,[])2Si8O40[O6,(OH)2] C 2/m 2/m

Strunz Class:

VIII/B.03-10 VIII - Silicates

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

VIII/B.03 - Staurolite - Gerstmannite series

VIII/B.03-03 Magnesiostaurolite! []4Mg4Al16(Al,[])2Si8O40[O6,(OH)2] C 2/m 2/m

VIII/B.03-05 Zincostaurolite! []4Zn4Al16(Al,[])2Si8O40[O6,(OH)2] C 2/m 2/m

VIII/B.03-10 Staurolite (Fe,Mg)2Al9(Si,Al)4O20(O,OH)4 C 2/m 2/m

VIII/B.03-20 Gerstmannite (Mg,Mn)2ZnSiO4(OH)2 Bbam 2/m 2/m 2/m

Other Staurolite Information

References:

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

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Staurolite

(Fe++,Mg)2Al9(Si,Al)4O20(O,OH)4
Dana No: 52.2.3.1 Strunz No: VIII/B.03-10
Locality:

Notes: