Cronstedtite Mineral Data

General Cronstedtite Information

Chemical Formula:

Fe++2Fe+++(SiFe+++)O5(OH)4

Composition:

Molecular Weight = 399.50 gm

Iron 55.92 % Fe 35.97 % FeO / 39.97 % Fe₂O₃

Silicon 7.03 % Si 15.04 % SiO₂

Hydrogen 1.01 % H 9.02 % H₂O

Oxygen 36.04 % O

______ ______

100.00 % 100.00 % = TOTAL OXIDE

Empirical Formula:

Fe²⁺₂Fe³⁺₂SiO₅(OH)₄

Environment:

A low-temperature hydrothermal product in ore veins.

IMA Status:

Valid Species (Pre-IMA) 1821

Locality:

Pribram and Kuttenberg, Bohemia of Czechoslovakia. Link to MinDat.org Location Data.

Name Origin:

Named for Axel Fredrik Cronstedt (1722-1765), Swedish mineralogist and chemist.

Name Pronunciation:

Cronstedtite + Pronunciation

Cronstedtite Image

Images:

Cronstedtite

Comments: Pyramidal crystals of cronstedtite.
Location: Santa Eulalia, Chihuahua, Mexico. Scale: Not Given.
© Lou Perloff / Photo Atlas of Minerals

Cronstedtite Crystallography

Axial Ratios:

a:c = 1:1.29329

Cell Dimensions:

a = 5.486, c = 7.095, Z = 1; V = 184.92 Den(Calc)= 3.59

Crystal System:

Trigonal - Ditrigonal PyramidalH-M Symbol (3m) Space Group: P 3₁m

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

By Intensity(I/I_o): 2.56(1), 7.1(0.9), 3.548(0.6),

Crystal Structure:

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Hendricks S B , American Mineralogist , 24 (1939) p.529-539, Random structures of layer minerals as illustrated by cronstedtite, (2FeO.Fe2O3.SiO2.2H2O). Possible iron content of kaolin

View Additional jPOWD Structure files for Cronstedtite
[1] [2] [3] [4]

Physical Properties of Cronstedtite

Cleavage:

{001} Perfect

Color:

Brownish black, Greenish black, Dark brown, Black.

Density:

3.34 - 3.35, Average = 3.34

Diaphaneity:

Transparent to translucent

Habit:

Amorphous - No crystalline form or imitative shape.

Habit:

Divergent - Crystals radiate from a center without producing stellar forms.

Habit:

Pyramidal - Crystals are shaped like pyramids.

Hardness:

3.5 - Copper Penny

Luster:

Vitreous - Resinous

Streak:

dark olive green

Optical Properties of Cronstedtite

Gladstone-Dale:

CI meas= 0.095 (Poor) - where the CI = (1-KPDmeas/KC)
CI calc= 0.157 (Poor) - where the CI = (1-KPDcalc/KC)
KPDcalc= 0.2154,KPDmeas= 0.2312,KC= 0.2555
Ncalc = 1.85 - 1.92

Optical Data:

Biaxial (-), a=1.72, b=1.8, g=1.8, bire=0.0800, 2V(Calc)=0, 2V(Meas)=0.

Calculated Properties of Cronstedtite

Electron Density:

Bulk Density (Electron Density)=3.25 gm/cc
note: Specific Gravity of Cronstedtite =3.35 gm/cc.

Fermion Index:

Fermion Index = 0.01
Boson Index = 0.99

Photoelectric:

PE_Cronstedtite= 17.04 barns/electron
U=PE_Cronstedtite x rElectron Density= 55.37 barns/cc.

Radioactivity:

GRapi = 0 (Gamma Ray American Petroleum Institute Units)
Cronstedtite is Not Radioactive

Cronstedtite Classification

Dana Class:

71.01.02c.07 (71)Phyllosilicate Sheets of Six-Membered Rings

(71.01)with 1:1 layers

(71.01.02c)Serpentine group (Amesite subgroup)

71.01.02c.01 Amesite Mg2Al(SiAl)O5(OH)4 C1 1

71.01.02c.02 Berthierine (Fe,Fe,Al,Mg)2-3(Si,Al)2O5(OH)4 Cm m

71.01.02c.03 Brindleyite (Ni,Mg,Fe)2Al(SiAl)O5(OH)4 C 2 2

71.01.02c.04 Fraipontite (Zn,Al)3(Si,Al)2O5(OH)4 Cm m

71.01.02c.05 Kellyite (Mn,Mg,Al)3(Si,Al)2O5(OH)4 P 6₃ 6

71.01.02c.06 Manandonite Li2Al4[(Si2AlB)O10](OH)8 C1 1

71.01.02c.07 Cronstedtite Fe2Fe(SiFe)O5(OH)4 P 3₁m 3m

Strunz Class:

09.ED.15 09 - SILICATES (Germanates)

09.E - Phyllosilicates

09.ED -Phyllosilicates with kaolinite layers

09.ED.15 Clinochrysotile? Mg3Si2O5(OH)4 Cc, C 2/m Mono

09.ED.15 Berthierine (Fe,Fe,Al,Mg)2-3(Si,Al)2O5(OH)4 Cm m

09.ED.15 Brindleyite (Ni,Mg,Fe)2Al(SiAl)O5(OH)4 C 2 2

09.ED.15 Amesite Mg2Al(SiAl)O5(OH)4 C1 1

09.ED.15 Antigorite (Mg,Fe)3Si2O5(OH)4 Cm m

09.ED.15 Caryopilite (Mn,Mg,Zn,Fe)3(Si,As)2O510(OH,Cl)4 Cm or C 2/m Mono

09.ED.15 Fraipontite (Zn,Al)3(Si,Al)2O5(OH)4 Cm m

09.ED.15 Cronstedtite Fe2Fe(SiFe)O5(OH)4 P 3₁m 3m

09.ED.15 Chrysotile Mg3Si2O5(OH)4 A2/m 2/m

09.ED.15 Nepouite Ni3Si2O5(OH)4 Ccm21 mm2

09.ED.15 Greenalite (Fe,Fe)2-3Si2O5(OH)4 Unk Mono

09.ED.15 Kellyite (Mn,Mg,Al)3(Si,Al)2O5(OH)4 P 6₃ 6

09.ED.15 Maufite? (Mg,Ni)Al4Si3O13•4(H2O)(?) Mono ? Mono

09.ED.15 Lizardite Mg3Si2O5(OH)4 P1 1

09.ED.15 Orthochrysotile? Mg3Si2O5(OH)4 Unk Ortho

09.ED.15 Manandonite Li2Al4[(Si2AlB)O10](OH)8 C1 1

09.ED.15 Pecoraite Ni3Si2O5(OH)4 C 2/m 2/m

09.ED.15 Parachrysotile? Mg3Si2O5(OH)4 Unk Ortho

Other Cronstedtite Information

References:

NAME( AntBidBlaNic2) PHYS. PROP.(Enc. of Minerals,2nd ed.,1990) OPTIC PROP.(Enc. of Minerals,2nd ed.,1990)

See Also:

Links to other databases for Cronstedtite :
1 - Am. Min. Crystal Structure Database
2 - Athena
3 - EUROmin Project
4 - Ecole des Mines de Paris
5 - GeoScienceWorld
6 - Google Images
7 - Google Scholar
8 - Handbook of Mineralogy (MinSocAm)
9 - Handbook of Mineralogy (UofA)
10 - MinDAT
11 - Mineralienatlas (Deutsch)
12 - Online Mineral Museum
13 - QUT Mineral Atlas
14 - Ruff.Info
15 - WWW-MINCRYST

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

Cronstedtite

Fe++2Fe+++(SiFe+++)O5(OH)4
Dana No: 71.01.02c.07 Strunz No: 09.ED.15
Locality:

Notes: