Fougèrite (original) (raw)

A valid IMA mineral species

About FougèriteHide

This section is currently hidden. Click the show button to view.

Formula:

Fe2+4Fe3+2(OH)12[CO3] · 3H2O

Colour:

Bluish green, green, green-black, blackish

Name:

Named for "a forest near Fougères, Brittany, France", where the type material was collected.

The mineral formerly described as fougèrite has been found to be an intimate intergrowth of two phases with distinct Fe2+:Fe3+ ratios. The phase with Fe2+:Fe3+ = 2:1 retains the name fougèrite; that with Fe2+:Fe3+ = 1:2 is defined as the new species trébeurdenite. Both belong to the Fougèrite Group (Mills et al., 2012).

Fougèrite is unstable in air at normal conditions (Trolard et al., 2007); the green (or green-black, blackish), hexagonal, transparent platelets transform quickly into yellow-brown to brown, opaque, often poorly crystalline, brittle iron oxyhydroxides (limonite, goethite, lepidocrocite). Known previously as "Green Rust", mainly from iron-rich slags.

Varieties containing Zn retain their green colour and transparency (Blaß et al., 1997).

The characteristic blue-green colour (5BG6/1 in the Munsell system) of fougèrite has long been used as a universal criterion in soil classification to identify Gleysols (Trolard et al., 2007).

One of six minerals proposed to be essential for life emergence. Actually, one of two "vital" candidates due to "comprising precipitate membrane", the other one being mackinawite (Russell & Pone, 2020).

Unique IdentifiersHide

This section is currently hidden. Click the show button to view.

Long-form identifier:

mindat:1:1:27543:3

bb2cb014-2054-49fb-a871-ed0569575187

IMA Classification of FougèriteHide

This section is currently hidden. Click the show button to view.

IMA Formula:

Fe2+4Fe3+2(OH)12(CO3) · 3H2O

Type description reference:

Trolard, F., Bourrié, G., Abdelmoula, M., Refait, Ph., Feder, F. (2007): Fougerite, a new mineral of the pyroaurite-iowaite group: description and crystal structure. Clays and Clay Minerals, 55, 323-334.

Classification of FougèriteHide

This section is currently hidden. Click the show button to view.

4.FL.05

4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
F : Hydroxides (without V or U)
L : Hydroxides with H2O +- (OH); sheets of edge-sharing octahedra

6.4.6.2

6 : HYDROXIDES AND OXIDES CONTAINING HYDROXYL
4 : Miscellaneous

Mineral SymbolsHide

This section is currently hidden. Click the show button to view.

As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.

Physical Properties of FougèriteHide

This section is currently hidden. Click the show button to view.

Colour:

Bluish green, green, green-black, blackish

Comment:

Only when fresh; alters within hours and days

Chemistry of FougèriteHide

This section is currently hidden. Click the show button to view.

Mindat Formula:

Fe2+4Fe3+2(OH)12[CO3] · 3H2O

Crystallography of FougèriteHide

This section is currently hidden. Click the show button to view.

Class (H-M):

3_m_ _(_32/m ) - Hexagonal Scalenohedral

Cell Parameters:

a = 3.125 Å, c = 22.5 Å

Unit Cell V:

190.29 ų (Calculated from Unit Cell)

X-Ray Powder DiffractionHide

This section is currently hidden. Click the show button to view.

Powder Diffraction Data:

Geological EnvironmentHide

This section is currently hidden. Click the show button to view.

Type Occurrence of FougèriteHide

This section is currently hidden. Click the show button to view.

General Appearance of Type Material:

Small crystals (400-500 nm) in the form of hexagonal plates.

Place of Conservation of Type Material:

Geological Setting of Type Material:

Subsurface horizon of a Gleysol soil. Partial oxidation and hydrolysis of aqueous Fe2+.

Associated Minerals at Type Locality:

Reference:

Trolard, F., Bourrié, G., Abdelmoula, M., Refait, Ph., Feder, F. (2007) Fougerite, a new mineral of the pyroaurite-iowaite group: description and crystal structure. Clays and Clay Minerals: 55: 323-334.

Synonyms of FougèriteHide

This section is currently hidden. Click the show button to view.

Relationship of Fougèrite to other SpeciesHide

This section is currently hidden. Click the show button to view.

Other Members of this group:

Common AssociatesHide

This section is currently hidden. Click the show button to view.

Associated Minerals Based on Photo Data:

Related Minerals - Strunz-mindat GroupingHide

This section is currently hidden. Click the show button to view.

Fluorescence of FougèriteHide

This section is currently hidden. Click the show button to view.

Other InformationHide

This section is currently hidden. Click the show button to view.

Notes:

Unstable in air and transforms to lepidocrocite or goethite.

Health Risks:

No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

Internet Links for FougèriteHide

This section is currently hidden. Click the show button to view.

References for FougèriteHide

This section is currently hidden. Click the show button to view.

Reference List:

Trolard, F., Abdelmoula, M., Bourrie, G., Humbert, B., Genin, J. (1996) Evidence of the occurrence of a 'green rusts' component in hydromorphic soils. Proposed existence of a new mineral fougerite. CRAS (Paris), serie IIa: 232: 1015-1022.

Génin, J.-M. R., Aïssa, R., Géhin, A., Abdelmoula, M., Benali, O., Ernstsen, V., Ona-Nguema, G., Upadhyay, Ch., Ruby, Ch. (2005) Fougerite and FeII-III hydroxycarbonate green rust; ordering, deprotonation and/or cation substitution; structure of hydrotalcite-like compounds and mythic ferrosic hydroxide Fe(OH)2+x. Solid State Sciences: 7: 545-572.

Trolard, F., Bourrié, G., Abdelmoula, M., Refait, Ph., Feder, F. (2007): Fougerite, a new mineral of the pyroaurite-iowaite group: description and crystal structure. Clays and Clay Minerals, 55, 323-334.

Christiansen, B.C., Balić-Žunić, T., Petit, P.-O., Frandsen, C., Mørup, S., Geckeis, H., Katerinopoulou, A., Svane Stipp, S.L. (2009) Composition and structure of an iron-bearing, layered double hydroxide (LDH) - Green rust sodium sulphate. Geochimica et Cosmochimica Acta: 73(12): 3579-3592.

Mills, S. J., Christy, A. G., Génin, J.-M. R., Kameda, T., Colombo, F. (2012) Nomenclature of the hydrotalcite supergroup: natural layered double hydroxides. Mineralogical Magazine, 76 (5) 1289-1336 doi:10.1180/minmag.2012.076.5.10

Localities for FougèriteHide

This section is currently hidden. Click the show button to view.

This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.

Locality ListHide

This section is currently hidden. Click the show button to view.

- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for references and further information on this occurrence. ? - Indicates mineral may be doubtful at this locality. - Good crystals or important locality for species. - World class for species or very significant. (TL) - Type Locality for a valid mineral species. (FRL) - First Recorded Locality for everything else (eg varieties). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (e.g. from pseudomorphs).

All localities listed without proper references should be considered as questionable.