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Hastings Co., Ontario, Canada
© 2008, JGW
|System:||Monoclinic||Colour:||Brown to black|
|Hardness:||2½ - 3|
|Name:||In allusion to its composition and crystal structure, containing iron 3+ cations (FERRIc, from Latin ferrum = 'iron') in TETRAhedrally coordinated sites, and its chemical relationship to annite.|
Mica Group. The ferric iron analogue of annite and ferrous iron analogue of tetraferriphlogopite.
The original name, ferri-annite, was changed by the CNMMN in 1998, Canadian Mineralogist 36, 905-12.
Classification of Tetraferriannite
|Strunz 8th edition ID:||8/H.11-120|
|Nickel-Strunz 10th (pending) edition ID:||9.EC.20|
9 : SILICATES (Germanates)
E : Phyllosilicates
C : Phyllosilicates with mica sheets, composed of tetrahedral and octahedral nets
|Dana 8th edition ID:||71.2.2b.4|
71 : PHYLLOSILICATES Sheets of Six-Membered Rings
2 : Sheets of 6-membered rings with 2:1 layers
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Type Occurrence of Tetraferriannite
|Type Locality:||Dales Gorge member Fe-formation, Wittenoom (Wittenoom Gorge), Ashburton Shire, Western Australia, Australia|
Physical Properties of Tetraferriannite
|Colour:||Brown to black|
|Hardness (Mohs):||2½ - 3|
Crystallography of Tetraferriannite
Optical Data of Tetraferriannite
|RI values:||nα = 1.660 nβ = 1.720 nγ = 1.728|
|Maximum Birefringence:||δ = 0.068|
Chart shows birefringence interference colour range (at 30µm thickness) and does not take into account mineral colouration.
Chemical Properties of Tetraferriannite
|Simplified for copy/paste:||KFe2+3((Fe3+,Al)Si3O10)(OH)2|
|Essential elements:||Fe, H, K, O, Si|
|All elements listed in formula:||Al, Fe, H, K, O, Si|
Relationship of Tetraferriannite to other Species
|Member of:||Mica Group|
|Other Members of Group:|
|Related Minerals - Nickel-Strunz Grouping):|
Other Names for Tetraferriannite
|Health Warning:||No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.|
References for Tetraferriannite
American Mineralogist (1982): 67: 1179-1194.
Canadian Mineralogist (1998): 36: 905-912.
Canadian Mineralogist article can also be found in:
The Nomenclature of Minerals: A Compilation of IMA Reports (1998) http://pubsites.uws.edu.au/ima-cnmnc/
Internet Links for Tetraferriannite
Localities for Tetraferriannite
The 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.
(TL) indicates type locality. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
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Locality Updated: Castro Laboreiro, Melgaço, Viana do Castelo District, PortugalFrom Rui Nunes, 30th Oct 2014 12:11:27